Singapore Math Strategies
( A Parent’s Guide)
We have been learning that all math problems have 2 parts that make the whole…
WHOLE
PART
PART
When finding the missing number in an equation, look at a math sentence and decide
which number is missing. (Math sentences are made up of “parts” and the “whole”.)
If you have 2 “parts” and you need to find the “whole”...then add.
?
15 + 36 = ____
15
36
If you have one “whole” and one “part”...then subtract. (Take the 14 away from 64...or...64 - 14).
64 - _____ = 14
64
?
14
We have been learning how to add and Subtract 2 digit and 3 digit Numbers…
***First make sure to line up the numbers according to the place values in any problem you do.
Adding Left to Right:
Hundreds
Tens
Ones
4
1
3
3
6
5
7
0
0
7
0
+
First, start to add with the hundreds column.
( 400 + 300 = 700)
Now add the tens. (10 + 60 = 70)
Then add the ones.
(3 + 5 = 8)
+
8
7
7
8
Hundreds
Tens
Ones
7
5
4
4
4
2
3
0
0
1
0
Subtracting Left to Right:
First, start subtracting with the hundreds column.
( 700 - 400 = 300)
Now subtract the tens. (50 + 40 = 10…but think of this as a positive or +10)
Then subtract the ones.
(4 - 2 = 2… but think of this as a positive or +2)
Now put all of the parts back together (add)
to finish the computation…
+
2
3
1
2
Branching Method for Addition:
9 + 4 =
Directions for branch method:
1. Set up problems horizontally.
1 3
2. If problem has two single digits to add, branch the second
number with a number bond.
3. Make a 10 and circle the 10.
10 + 3 = 13
4. Add the remaining 1s to the 10 to find the solution of the
problem.
Branching Method for two digit addition:
34 +
25 =
Directions for branch method 2-digit:
1. Set up problems horizontally.
30
4
5
20
2. Branch the numbers in 10s and 1s.
3. Put the 10s on the outside of the branch.
30 + 20 + 4 + 5 =
50 + 9 = 59
So…
4. Put the 1s on the inside of the branch.
5. Circle all the 10s.
6. Continue to branch and make 10s where appropriate.
Branching Method for two digit Subtraction:
43 -
12 =
Directions for branch method 2-digit:
1. Set up problems horizontally.
40
3
2
10
2. Branch the numbers in 10s and 1s.
3. Put the 10s on the outside of the branch.
4. Put the 1s on the inside of the branch.
40 – 10 = 30
3 – 2 = 1(think positive 1 or +1)
30 + 1 = 31
5. Circle all the 10s.
6. Subtract the 10s then subtract the 1s
7. Add the difference.
We have been learning how to find missing numbers totaling 100…
When finding the missing number in an equation totaling 100…
42 + ____ = 100
First count up to the next ten…(42 + 8 = 50)
From there...count by tens to 100...
( 50 + 50 = 100)
Then add 50 + 8 to get 58...the missing addend.
So… 42 + 58 = 100
Or another way is to think of it is…
Tens Ones
9
10
100 is really the same as 9 tens and 10 ones
53 + ____ = 100
100 - 53 = ____
5 tens 3 ones
+ __ tens __ ones
_9______10___(which is really 100)
Think…I need 4 more tens and 7 more ones to make 9 tens and 10 ones
So the answer is 47.
We have been Adding up from 98 and 99…
When adding from 98 or 99 …
99 + 156 = ____
Determine which number is closer to 100 and how many you need to get there…(99 is
closer and I need 1 more to make 100).
So think….99 + 156 =
1
155
99 + 1 makes 100 leaving me with 155...
100 + 155 = 255
So...99 + 156 = 255
We have been subtracting 98 and 99…
When subtracting 98 or 99 …
362 - 98 = ____
262
100
Subtracting 100 – 98 leaves me with 2…
So then…262 + 2 = 264
We have been Adding and subtracting mentally…
When adding or subtracting mentally, you need to break the second number down
into parts…
62 + 16 = ____
10
(First think...16 is really 10 and 6)
6
Next, add 10 + 62 =72.
Then add 72 + 6 to get the answer 78.
Or...
78 – 24 = ____
20
Next, subtract 78 - 20 = 58.
Then subtract 58 - 4 to get the answer 54.
4
(First think...24 is really 20 and 4)
We have been learning subtraction with branching…
When subtracting a two-digit number from a two-digit number...
67 – 24 = ____
Use branching by linking the numbers in the tens place together with a “branch”
and the numbers in the ones place together with another “branch”. Then subtract.
67 – 24 = ____
So think... 60 – 20 = 40
40 + 3 = 43
and...
7–4=3
(Since both numbers are positive, you link them by adding to get the answer.)
When subtracting with regrouping...
82 – 45 = _____
40 – 3 = 37
(Branch as before... but this
So think...80 – 40 = 40
and... 2 – 5 = -3
Now subtract.
time you will have negative
numbers)
When subtracting with three digit numbers...
645 – 281 = _____
400 – 40 + 4
Think... 600 – 200 = 400
40 – 80 = -40 (This is a negative number).
5 – 1 = +4 (This is a positive number).
So...400 – 40 = 360
And... 360 + 4 = 364
And of course … There is Model Drawing...
Make sure your child is using the 8 Steps of Model Drawing when solving word
problems at home.
8 Steps of Model Drawing
1.
Read the entire problem.
2.
Decide who the problem is about.
3.
Decide what is involved.
4.
Draw unit bars of equal length.
5.
Read the problem one sentence at a time.
6.
Put the ? in place.
7.
Work out the problem...show your work!
8.
Write your answer in a complete sentence.