Mathematics for IGCSE & O level - Estimation (Section 2 - No. 41)
What happens to the value of a number when rounded to 1 s.f. if the second digit is greater or equal to 5?
The first digit increases by 1
The number remains the same
The first digit decreases by 1
The number is rounded down to zero
Paliwanag
If the second digit is 5 or greater, increase the first significant figure by 1.