Mental Arithmetic

Do this exercise mentally. In other words, you should not use a calculator or a pen/cil and paper.

7 + 3 =
1. 4
2. 8
3. 9
4. 10
9 - 2 =
8/2 =
3 x 3 =
25 + 16 =
62 + 7 =
54 - 17 =
23 + 22 =
39 - 18 =
36 785 - 188 =
72 + 98 - 17 =
376 - 360 + 337 =
444 + 332 - 216 =
2 710 + 4 370 − 400 =
| 7 | =

FYI The operators | | stand for 'absolute value' and signify the distance away from zero on the numberline.
7 777 − 3 443 + 1 173 =