Answer
340
Work Step by Step
To add numbers on a calculator, first locate the buttons marked +, and = or ENTER. To add two numbers, input the first number you wish to add, then press the + button. Then input the second number you wish to add, then press the = or ENTER button. To add 285+55, press the following buttons in the following order:
2, 8, 5, +, 5, 5, =
