Complete the sum: 11 Plus verbal reasoning practice
Find the number that makes both sides equal.
OftenIn many papers, especially GL AssessmentAbout 35 seconds a question in the test
The big idea
A sum has two sides and an equals sign, and one number is missing. The two sides must be worth the same, so work out the side with no gap first.
The classic slip is to write the value of the first side as the answer. The answer is the number that makes the other side reach that value.
Tips that save marks
Work out the complete side and write its value above the equals sign.
Then ask: what does the other side need to make that value?
Check by putting your number in the gap and working out both sides.
A worked example
6 + 3 = 12 − ?
The left side is 6 + 3 = 9.
The right side must also be 9: 12 − ? = 9.
12 − 3 = 9, so the missing number is 3 (not 9).
Now try five
Try each one before you look at the answer: answering from memory is what makes it stick. Tap an option to check it. Most children get three or four right at first; five out of five means move on to the next topic.
Question 1Aim for about 35 seconds
Find the number that makes both sides of the sum equal.
80 − 7 = 146 ÷ ?
Show the worked answer
Answer: B, 2
How to work it out
Work out the side with no gap: 80 − 7 = 73.
The other side must also make 73: 146 ÷ 2 = 73.
The missing number is 2.
Why the other options are wrong
A (73): 73 is the value of the left side, not the missing number. Put 73 in the gap and the right side makes 2, not 73.
C (1): With 1 in the gap the right side makes 146, not 73. Both sides must be equal.
D (146): With 146 in the gap the right side makes 1, not 73. Both sides must be equal.
E (219): With 219 in the gap the right side makes 0.67, not 73. Both sides must be equal.
Question 2Aim for about 35 seconds
Find the number that makes both sides of the sum equal.
20 + 14 = 2 × ?
Show the worked answer
Answer: E, 17
How to work it out
Work out the side with no gap: 20 + 14 = 34.
The other side must also make 34: 2 × 17 = 34.
The missing number is 17.
Why the other options are wrong
A (2): With 2 in the gap the right side makes 4, not 34. Both sides must be equal.
B (32): With 32 in the gap the right side makes 64, not 34. Both sides must be equal.
C (34): 34 is the value of the left side, not the missing number. Put 34 in the gap and the right side makes 68, not 34.
D (36): With 36 in the gap the right side makes 72, not 34. Both sides must be equal.
Question 3Aim for about 35 seconds
Find the number that makes both sides of the sum equal.
45 + 22 = 75 − ?
Show the worked answer
Answer: E, 8
How to work it out
Work out the side with no gap: 45 + 22 = 67.
The other side must also make 67: 75 − 8 = 67.
The missing number is 8.
Why the other options are wrong
A (142): With 142 in the gap the right side makes −67, not 67. Both sides must be equal.
B (75): With 75 in the gap the right side makes 0, not 67. Both sides must be equal.
C (67): 67 is the value of the left side, not the missing number. Put 67 in the gap and the right side makes 8, not 67.
D (1): With 1 in the gap the right side makes 74, not 67. Both sides must be equal.
Question 4Aim for about 35 seconds
Find the number that makes both sides of the sum equal.
18 + 17 = 53 − ?
Show the worked answer
Answer: A, 18
How to work it out
Work out the side with no gap: 18 + 17 = 35.
The other side must also make 35: 53 − 18 = 35.
The missing number is 18.
Why the other options are wrong
B (1): With 1 in the gap the right side makes 52, not 35. Both sides must be equal.
C (35): 35 is the value of the left side, not the missing number. Put 35 in the gap and the right side makes 18, not 35.
D (88): With 88 in the gap the right side makes −35, not 35. Both sides must be equal.
E (53): With 53 in the gap the right side makes 0, not 35. Both sides must be equal.
Question 5Aim for about 35 seconds
Find the number that makes both sides of the sum equal.
56 − 18 = ? ÷ 3
Show the worked answer
Answer: C, 114
How to work it out
Work out the side with no gap: 56 − 18 = 38.
The other side must also make 38: 114 ÷ 3 = 38.
The missing number is 114.
Why the other options are wrong
A (35): With 35 in the gap the right side makes 11.67, not 38. Both sides must be equal.
B (38): 38 is the value of the left side, not the missing number. Put 38 in the gap and the right side makes 12.67, not 38.
D (41): With 41 in the gap the right side makes 13.67, not 38. Both sides must be equal.
E (3): With 3 in the gap the right side makes 1, not 38. Both sides must be equal.
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