Number bonds are one of those things that seem to produce unusual passion and concern in young mathematicians and their parents.
The name's Bond, Number Bond (Image:Wikipedia)
Parents and students often ask us if we do number bonds, at Maths-Whizz, as though they are mathematical methods exclusive to the initiated few. Nothing could be further from the truth.
Number bonds are, in short, pairs of numbers that combine to make a third. Number bonds help show that every whole number larger than one is made up of other whole numbers. 1 & 4, 2 & 3 both make five. They are the number bonds of five.
Number bonds are vital for mental arithmetic. When you ‘partition’, or ‘decompose’ a number you get number bonds..
For instance, knowing that can be 15 can be partitioned to 10 and 5 helps you perform calculations with 15. You can calculate with the ’10′ part, and then with the ’5′ part, and combine their answers. 5 and 10 are number bonds of 15.
Knowing and remembering the number bonds of 100 makes it easier to handle money, or give change. If I know that 70 and 30 are number bonds of 100, then I know instantly how much change to expect from a pound when I buy a 70p packet of sweets.
Number bonds can help you add. Knowing that 5 and 2 are number bonds of 7 makes adding 7 to five much faster. Add five to five to get 10, and then add the remaining two to get 12! And this is just scratching the surface.
In Maths-Whizz we don’t refer to ‘number bonds’, but we do talk about partitioning numbers, about finding pairs of numbers, about mental methods that require an understanding of number bonds, and so forth.
Dozens of our lessons rely on knowledge of number bonds, and at least ten specifically test rapid recall of number pairs, and missing numbers. We even test more advanced students on splitting a whole number into two decimals.
You can try one such number bond speed game on our maths addition page. Scroll down to Year 5, and click the right-hand lesson image.
Click to try a free number bonds speed game
Get busy number bonding!
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