Arithmetic Grade Six

Lesson Twenty-seven: Number Chains

Sometimes we are presented with a sequence of numbers which we must add together: 


	3 + 6 + 4 + 7 + 5 =
Often you can save time with problems like this if you look for number combinations which add up to ten or multiples of ten. For instance, in this problem, 3 and 7 make 10 and 6 and 4 make 10. That leaves you with 10 + 10 + 5 which is easy to add up: 

	3 + 6 + 4 + 7 + 5 = 25
Here's another problem for you to try out: 

	27 + 12 + 13 + 18 + 5 =
Here it is easy to combine 27 and 13 and get 40. Next it is easy to combine 12 and 18 and get 30. This leaves you with 40 + 30 + 5 which is easy to add up to 75.

Not all problems work out as nicely as this, but looking for combinations like this can sometimes save you time and result in greater accuracy.

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