Subtraction
Subtraction
How can we progress with subtraction? Can we use different objects to help us understand subtraction? I have 6 strawberries. If I eat 2 of the, how many strawberries will I have left?
Can we use numbered lines to help count back? 11 - 5 = 6
0 1 2 3
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Can we use a number line to count back bridging through ten? 15 – 7 = 8 -2
8
10
-5
15
What if it was a harder subtraction question? 74 – 27 = 47
47
-20
-4
-3
50
54
74
Can I use my number line to find the difference between two numbers by counting on? I have chosen to count on here because the numbers are close together!
74 – 57 = 17 +10
+3
57
60
+4
70
=17
74
Can I partition numbers and place them into a vertical column method to subtract? T U 7 8 - 2 6
T 7 0 - 2 0 5 0
U 8 6 2
=52
No red alert as I can take 6 away from 8
How about when the units are smaller on the top row and I need to carry out decomposition? Red alert! I can’t take 7 away from 4
T U 7 4 - 2 7
T 7 0 - 2 0
U 4 7
6
0
14
7 0 - 2 0 4 0
4 7 7
No red alerts!
Can I try this method with bigger numbers? 788 – 367 =
H 7 0 0 - 3 0 0 4 0 0
T 8 0 6 0 2 0
=47
U 8 7 1
=421 Red alerts!
741 – 367 =
6
0
0
7 0 0 - 3 0 0 3 0 0
13 0
4 0 6 0 7 0
11
1 7 4
=374
Don’t forget, we can go back to the counting on strategies with a number line if the question has two numbers close together! 402 – 390 = 12 +10
390
+2
=12
400 402 5003 – 4995 = 8 +5 +3
4995
=8
5000 5003
Can I use my knowledge of subtraction to place my workings into the compact vertical method?
Red alert! Even with the difficult ones with zero!
4
15
5 6 13 - 2 7 8 2 8 5
4
9
5 10 13 - 2 7 8 2 2 5
Can we put our subtraction questions into the compact vertical method, if the number has decimal places or they are larger numbers? 16.5kg – 5.49kg = 11.01kg 12,367 – 1,928 = 10,439 4
1 6 . 5 10 - 0 5 . 4 9 1 1 . 0 1 kg
Don’t forget to write the units you are working with!
1
1
5
1 2 3 6 17 - 0 1 9 2 8 1 0 4 3 9
How can we progress with subtraction? Can we use different objects to help us understand subtraction? I have 6 strawberries. If I eat 2 of the, how many strawberries will I have left?
Can we use numbered lines to help count back? 11 - 5 = 6
0 1 2 3
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Can we use a number line to count back bridging through ten? 15 – 7 = 8 -2
8
10
-5
15
What if it was a harder subtraction question? 74 – 27 = 47
47
-20
-4
-3
50
54
74
Can I use my number line to find the difference between two numbers by counting on? I have chosen to count on here because the numbers are close together!
74 – 57 = 17 +10
+3
57
60
+4
70
=17
74
Can I partition numbers and place them into a vertical column method to subtract? T U 7 8 - 2 6
T 7 0 - 2 0 5 0
U 8 6 2
=52
No red alert as I can take 6 away from 8
How about when the units are smaller on the top row and I need to carry out decomposition? Red alert! I can’t take 7 away from 4
T U 7 4 - 2 7
T 7 0 - 2 0
U 4 7
6
0
14
7 0 - 2 0 4 0
4 7 7
No red alerts!
Can I try this method with bigger numbers? 788 – 367 =
H 7 0 0 - 3 0 0 4 0 0
T 8 0 6 0 2 0
=47
U 8 7 1
=421 Red alerts!
741 – 367 =
6
0
0
7 0 0 - 3 0 0 3 0 0
13 0
4 0 6 0 7 0
11
1 7 4
=374
Don’t forget, we can go back to the counting on strategies with a number line if the question has two numbers close together! 402 – 390 = 12 +10
390
+2
=12
400 402 5003 – 4995 = 8 +5 +3
4995
=8
5000 5003
Can I use my knowledge of subtraction to place my workings into the compact vertical method?
Red alert! Even with the difficult ones with zero!
4
15
5 6 13 - 2 7 8 2 8 5
4
9
5 10 13 - 2 7 8 2 2 5
Can we put our subtraction questions into the compact vertical method, if the number has decimal places or they are larger numbers? 16.5kg – 5.49kg = 11.01kg 12,367 – 1,928 = 10,439 4
1 6 . 5 10 - 0 5 . 4 9 1 1 . 0 1 kg
Don’t forget to write the units you are working with!
1
1
5
1 2 3 6 17 - 0 1 9 2 8 1 0 4 3 9
