Question

Estimate Sums::

Use rounding or compatible numbers to estimate the sum.

222
+
203

Answer 1

425

Explanation:

just stack then and 2+2=4, 2+0=2, last 2+3=5 and done

Answer 2

225

Explanation:

The rounding system is used by rounding the numbers so by rounding the method would be:

`222=200 after-rounding\\203=200 after rounding\\rounding sum=220`

And compatible numbers would be rounding to the nearest five:

`222=220 after-rounding\\203=205 after rounding\\rounding sum=225`

So the compatible numbers gives you the exact answer but it´s not always this way.