Answer: Hello mate!
We have the equation 7.35+ 1.47+ 9.65
We can see that 35 + 65 = 100, so we could do this:
7.35+ 1.47+ 9.65 = (7.35+ 9.65) + 1.47 = (7 + 0.35+ 9 + 0.65) + 1.47 = (7 + 9 + (0.35 + 0.65)) + 1.47 = (7 + 9 + 1) + 1.47 = 17 + 1.47 = 18.47
Is always useful to look for numbers that "fit" and add them first.
With "fit" i mean that the numbers add to 1, 10 or something that is easier to handle.