Order of operations and brackets · Usually met around P3
Two-step word problems
Find the missing amount first, then the total.
How to do it
Method
Find the missing amount first, then the total
35 − 8 = 27, 35 + 27 = 62
Another way
One number sentence
35 + (35 − 8) = 62
In full
Draw a bar model first: A has 35, B has 8 fewer, so B's bar is a bit shorter. To find how many they have altogether, take two steps: first B, 35 − 8 = 27; then the total, 35 + 27 = 62. “More than” adds and “fewer than” takes away — but read carefully who is compared with whom: B has 8 fewer than A means A has 8 more than B. Or write one number sentence: 35 + (35 − 8) = 62. Check: 27 is 8 fewer than 35, and 27 + 35 = 62.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
Tsz-ching has 25 stamps. Chi-keung has 3 more than Tsz-ching. How many does Chi-keung have?
Show the answer and working
Answer: 28 stamps
3 more than 25: 25 + 3 = 28.
Example 2
Ka-lok has 44 sweets. Ka-yan has 13 fewer than Ka-lok. Ka-yan has □, and together they have □.
Fill in each box
Show the answer and working
Answer: 31，75
First Ka-yan: 44 − 13 = 31; then the total: 44 + 31 = 75.
Example 3
May has 53 cards and Ka-yee has 18 fewer, so together they have 71.
True or false?
Show the answer and working
Answer: False
Ka-yee has 53 − 18 = 35; together 53 + 35 = 88.
Practise it in the game →Order of operations and brackets · Free to start, unlimited questions, no download