Chains

Arithmetic Grade Four

Information:
You need to scan through a chain of numbers to recognize the possible short-cuts. Inspect this chain of numbers.


     28 + 34 + 33 + 17 + 22 =

You should notice that 28 + 22 = 50 and 33 + 17 = 50. That leaves the 34 unmatched and so you just solve 50 + 50 + 34 = 134 for the final sum.

Here's another example:


     17 + 25 + 52 + 23 + 18 =

Here you should notice that 52 + 18 = 70 and 17 + 23 = 40. These two sub-sums plus the unmatched 25 gives us a total sum of 135.