Commutative rules - smart exchanges of numbers (exchanging rules)

Commutative rules
Smart exchanges of numbers (exchanging rules)

[German] [English]

In addition and multiplication you can sometimes cleverly make advantages by exchanging sums and factors.

Example:

263 + 598 + 225 + 1 402 + 137 + 375

First, you check which of the numbers can be combined with others.

263 + 598 + 225 + 1 402 + 137 + 375

Second, you can neatly write it together but of course you don’t have to. Then, you add the single pairs and afterwards, the results together.

The result is 3 000. Who would have thought of that?

2. Example:

1) 5 · 125 · 20 · 8 · 10

2) = 20 · 5 · 125 · 8 · 10

3) = 100 · 1 000 · 10

= 1 000 000 (1 Million!)