Calculate the Hours We need an equation to add up all of our hours. All good equations start with “=.” 2. Try it: Calculate the Sum In Cell G2 type:  =SUM(A2:F2) Try This, As Well: Verify Your Work Say you worked 8 hours on Monday, Wednesday and Friday. In Cell A2, C2 and E2 type: 8 Does the Sum equal 24?   Keep going... Home ->Edit ->Sum