This question is about significant numbers and rounding up. Who can give me the correct answer to this?

Question

104.630 + 27.08362 + 0.61 =

Answer A = 132
Answer B = 132.3
Answer C = 132.32

wow, two hours and no answer, are all the maths teachers on holidays now?

Answer 1

Answer C is correct. When adding or subtracting, restrict the answer to the number with the least absolute precision - that is, the fewest digits after the decimal point (if they all have decimal parts).

e.g. 100.00000 + 6.013 = 106.013
1024.3 + 6.0256 = 1030.3
163400 + 835000 = 998000 (to see this, scale them by the same power of 10 so that they both have decimal parts: e.g. 16.34×10^4 + 83.5×10^4 = 99.8×10^4.)

When multiplying or dividing, you do it differently. Here we are concerned with relative precision, i.e. the number of significant digits. Restrict the answer to the minimum number of significant digits in the numbers given.