marvy math strategies
DESCRIPTION
Here is a ppt about basic addition and subtraction fact strategies. A "must see" for elementary classrooms!TRANSCRIPT
Tricks & Shortcuts to Adding & Subtracting Basic Facts
By Vicki Dabrowka ~ Eagle Cove School
www.eaglecoveschool.org
Marvy Math
Strategies
Zero Facts
Could it get any easier??Zero is a mirror.
Anything plus or minus 0 is itself!
Zero Facts
327 + 0 = ___
0 + 2,748 = ______
42,892 – 0 = _______
5,000,000 – 5,000,000 = _
Zero Facts
327 + 0 = 327
0 + 2,748 = 2,748
42,892 – 0 = 42,892
5,000,000 – 5,000,000 = 0
Count Ons
Anything +1, +2, +3, +4
Count Ons
7 + 4 = ____
Anything +1, +2, +3, +4
Count Ons
7 + 4 = Think “7,” Then count on: 8, 9, 10,
11
49 + 3 = __
Anything +1, +2, +3, +4
Count Ons
49 + 3 = 52
128 + 4 = ___
Anything +1, +2, +3, +4
Count Ons
128 + 4 = 132
Remember:Anything +1, +2, +3,
+4
Count Backs
Anything -1, -2, -3, -4
Count Backs
13 – 4 = _____
Anything -1, -2, -3, -4
Count Backs
13 – 4 = Think “13”Then count on: 12, 11, 10,
9
15 – 3 = ____
Anything -1, -2, -3, -4
Count Backs
15 – 3 = 12
31 – 2 = ____
Anything -1, -2, -3, -4
Count Backs
31 – 2 = 29
383 – 4 = ____
Anything -1, -2, -3, -4
Count Backs
383 – 4 = 379
Remember:Anything -1, -2, -3, -4
Count Ups
11 - 8
“Count Ups” are 2 numbers in subtract that are pretty close
together… it’s kind of the opposite of a Count Back &
the answer is usually 1, 2, 3, 4.
Count Ups
11 - 8
Start with the littlest number & COUNT UP to the larger one
(clapping tends to help!)
Count Ups
11 – 8 = __ 8…….9, 10, 11 You
counted up 3 times!
Remember: Start with the littler number & COUNT UP to the larger one. (Did you clap
or tap the desk too? It really helps!)
Count Ups
11 – 8 = 3 8…….9, 10, 11 You
counted up 3 times!
It’s true!Now try a few!
Count Ups
15 – 11 = __
Start with the littler one & COUNT UP
to the larger one.
Count Ups
15 – 11 = 4
11…12, 13, 14, 15
You counted up 4 times.
Count Ups
51 – 47 = __
Start with the littler number & COUNT UP
to the larger one.
Count Ups
51 – 47 = 4
47….48, 49, 50, 51You counted up 4 times.
It works for any 2 numbers that are close together!
10 Frame
Knowing your Facts of 10 or thinking of the 10 Frame picture
helps a ton! It’s like a short egg carton with exactly 10
spots.
10 Frame
We all know that 5 + 5 = 10 and 10 – 5 = 5…
use that information to help you visualize a 10 frame & fill the
frame!
10 Frame
__ + __ = 10
10 - __ = __
10 Frame
__ + __ = 10
10 - __ = __
10 Frame
__ + __ = 10
10 - __ = __
10 Frame
__ + __ = 10
10 - __ = __
Lock in some mental pictures of things that naturally come in doubles. Then, think of these
double pictures to help you with your math facts!
Doubles
1 + 1 = _
Eyes
1 + 1 = _
2 Eyes
1 + 1 = 2
2 + 2 = _
2 + 2 = _
__ Wheels
2 + 2 = 4
4 Wheels
3 + 3 = _
3 + 3 = _
__ Clover leaves
3 + 3 = 6
6 Clover leaves
4 + 4 = _
4 + 4 = _
__ spider legs
4 + 4 = 8
8 spider legs
5 + 5 = _
5 + 5 =
__ fingers on 2 hands
5 + 5 = 10
10 fingers on 2 hands
6 + 6 = _
6 + 6 = __
__ eggs in a dozen
6 + 6 = 12
12 eggs in a dozen
7 + 7 = __
7 + 7 = __
__ days in 2 weeks on the calendar
7 + 7 = 14
14 days in 2 weeks on the calendar
8 + 8 = __
8 + 8 = __
__ tentacles on 2 octopus
8 + 8 = 16
16 tentacles on 2 octopus
9 + 9 = __
9 + 9 = __
__ Wheels on an 18-wheel semi truck
9 + 9 = 18
18 Wheels on an 18-wheel semi truck
Doubles for Subtract
Think of your Add Double pictures in
reverse! You’ve got to love
Fact Families!
Once you know your Doubles, this will be a
great strategy for you!!
It works for all of them! Here are just 2
examples.
Doubles + 1
Think of your double facts,
then add one more!
Doubles + 1
6 + 7 = ____
Think of your double facts, then add one more!
Doubles + 1
6 + 7 = ____
Think of your egg carton dozen, then add 1 more egg!
Doubles + 1
6 + 7 = 13 eggs
+
Think of your double facts, then add one more!
Doubles + 1
8 + 7 = ____
Think of your 2 weeks of 7 days,
then add 1 more day!
Doubles + 1
8 + 7 = ____
Think of your 2 weeks of 7 days,
then add 1 more day!
Doubles + 1
8 + 7 = 15 days
Think of your 2 weeks of 7 days, then add 1 more day!
Doubles + 1
Challenge yourself to make up some of your
own!Go for some tricky
ones!!
Doubles + 1
Easy 9’s for Add
This works for any
1-digit number plus the number 9.
Easy 9’s for Add
8 8 8+ 9 + 9 + 9 1 17
Put down a “1” to make a teenage numbers…Think of 1 less than the other
digit.
Easy 9’s for Add
6 4 7+ 9 + 9 + 9
Now you try a few.
Easy 9’s for Add
6 4 7+ 9 + 9 + 9
1 __ 1 __ 1 __
Put down the 1’s to make teenage numbers.
Easy 9’s for Add
6 4 7+ 9 + 9 + 9
1 __ 1 __ 1 __
Think 1 less than the other number. (Remember this
only works for 9’s.)
Easy 9’s for Add
6 4 7+ 9 + 9 + 9
15 1 __ 1 __
Think 1 less than the other number. (Remember this
only works for 9’s.)
Easy 9’s for Add
6 4 7+ 9 + 9 + 9
15 13 1 __
Think 1 less than the other number. (Remember this
only works for 9’s.)
Easy 9’s for Add
6 4 7+ 9 + 9 + 9
15 13 16
Think 1 less than the other number. (Remember this
only works for 9’s.)
Easy 9’s Subtract
Just like there’s an Easy 9 Addition,
there’s Easy 9 Subtract!
Easy 9’s Subtract
1 6 1 4 1 7 - 9 - 9 - 9
This works for any “teenage” number minus
9.
Easy 9’s Subtract
1 6 1 4 1 7 - 9 - 9 - 9
Put a tiny plus sign in between the two digits of
your teenage number.
Easy 9’s Subtract
1+6 1 4 1 7 - 9 - 9 - 9
Put a tiny plus sign in between the two digits of
your teenage number.
Easy 9’s Subtract
1+6 1+4 1 7 - 9 - 9 - 9
Put a tiny plus sign in between the two digits of
your teenage number.
Easy 9’s Subtract
1+6 1+4 1+7 - 9 - 9 - 9
Put a tiny plus sign in between the two digits of
your teenage number.
Easy 9’s Subtract
1+6 1+4 1+7 - 9 - 9 - 9
Add the two digits together—Voila! You’ve got your difference
—Remember, it only works for “-9”
Easy 9’s Subtract
1+6 1+4 1+7 - 9 - 9 - 9
7 Add the two digits together—
Voila! You’ve got your difference—
Remember, it only works for “-9”
Easy 9’s Subtract
1+6 1+4 1+7 - 9 - 9 - 9
7 5Add the two digits together—
Voila! You’ve got your difference—
Remember, it only works for “-9”
Easy 9’s Subtract
1+6 1+4 1+7 - 9 - 9 - 9
7 5 8Add the two digits together—
Voila! You’ve got your difference—
Remember, it only works for “-9”
Add Leftovers
If you know all of your addition strategies and use them…there
are only 3 leftover problems: Memorize them!
5 + 7 = 12 5 + 8 = 136 + 8 = 14
Add Leftovers
5 + 8 = __
Add Leftovers
5 + 8 = 13
Add Leftovers
8 + 6 = __
Add Leftovers
8 + 6 = 14
Add Leftovers
5 + 7 = __
Add Leftovers
5 + 7 = 12
Add Leftovers
Don’t forget about the turn arounds too!7 + 5 = __
8 + 5 = __6 + 8 = __
Add Leftovers
Don’t forget about the turn arounds too!7 + 5 = 12
8 + 5 = __6 + 8 = __
Add Leftovers
Don’t forget about the turn arounds too!7 + 5 = 12
8 + 5 = 136 + 8 = __
Add Leftovers
Don’t forget about the turn arounds too!7 + 5 = 12
8 + 5 = 136 + 8 = 14
10-Finger Subtract
When you’ve used all of your other subtract strategies, 10-Finger Subtract will come to
your rescue!
10-Finger Subtract
Imagine your right hand pointer fingernail as a
big ZERO!
10-Finger Subtract
Use your ZERO pointer-finger to turn a problem into a 10-frame & an easier 10’s fact so you can
solve a simpler problem 1st to help you solve a harder problem!
10-Finger Subtract
1 6- 7
Move your ZERO pointer finger to cover your math fact in order
turn your problem into a 10-frame, easier 10’s fact.
10-Finger Subtract
1 6- 7
Move your ZERO pointer finger to turn a
problem into a 10-frame 10’s fact.
10-Finger Subtract
1 6- 7
Now you have a new temporary problem:
10 – 7
10-Finger Subtract
1 6- 7
All of a sudden, it’s a way easier problem!
10 – 7 = 3
10-Finger Subtract
1 6- 7
Lock in the 3 from 10 minus 7 into your
brain…but wait! That’s not the answer!
10-Finger Subtract
1 6- 7
3 is still in your brain.Now lift your finger and
PEEK! What do you see?
10-Finger Subtract
1 6- 7
3 is still in your brain.When you peek you see a 6.
Now think “6 + 3 (still in your brain)
= ?? ”
10-Finger Subtract
1 6- 7
6 + 3 = 9
So….16 – 7 = 9
10-Finger Subtract
1 4- 8
Okay! You are ready to try a few more!
10-Finger Subtract
1 4- 8
14 – 8 becomes 10 – 8.10 – 8 = ??
10-Finger Subtract
1 4- 8
10 – 8 = 2 Lock in the 2!Now PEEK!
10-Finger Subtract
1 4- 8
You see 4! 4 + 2 = ??
10-Finger Subtract
1 4- 8
4 + 2 = 6
So………14 – 8 = 6!
10-Finger Subtract
1 1- 5
You do it!
10-Finger Subtract
1 1- 5
Think 10 – 5.Lock in the answer
in your brain.
10-Finger Subtract
1 1- 5
Now PEEK!1 + your brain number = ??
10-Finger Subtract
1 1- 5
Now PEEK!1 + your brain number = ??
11 – 5 = ??
Knowing Your Math Facts
are the Key to Future
Success in Math!
What are you going to do to lock and load
your math facts??
Go Forth, young
mathematician, and
memorize those basic math facts!
THE END!
Or is it the BEGINNING
of your success???