Add: 13 and 15
13 and 15 13 + 15 = 28
Add: -13 and 15
Add: 259 from 214
Add: -528 and -243
Add: -623 and 326
Add: 258 and -473
Subtract: -5 from 8
Subtract: -8 from -2
Subtract: -123 from 453
Subtract: 329 and -124
Subtract: -222 from 0