What is a sum?
What is a sum?
The sum of two numbers is the answer you get when you add them both together. So the sum of 5 and 4 is 9.
There was a time when teachers used the word 'sum' to name the following addition number sentence:
9 + 5 = 14
They would often then mistakenly use the same word to name these subtraction, multiplication and division number sentences:
9 - 4 = 5
7 x 3 = 21
80 ÷ 10 = 8
To get round this confusion, we now refer to all of the above (in bold) as number sentences.
Sums in KS1 and KS2 maths
Children in Key Stage 2 need to be familiar with the word 'sum' as it often comes up in mental maths tests. For example:
What is the sum of 6 and 12?
What is the sum of 8, 2 and 9?
They may also carry out word problems or investigations in maths lessons which rely on them being familiar with the word, for example:
Word problem:
Mary has £35 in one bank account and £82 in another. What is the sum of money in both her bank accounts?
Word problem answer: £117
Investigation:
I am thinking of a two-digit number. The sum of both its digits is 9. The number is bigger than 50 and a multiple of 9. What could it be?
Investigation answer: 54, 63, 72, 81 or 90
Children need to be exposed to a variety of mathematical vocabulary as often as possible, rather than just seeing numbers and symbols.
