Rounding is the act of replacing a number with values that are an approximation.
- can be used to create simpler, or more explicit answers
Basic rounding rules:
1. If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up. Example: 68 rounded to 1 significant figure would be 70.
2. If the number you are rounding is followed by 0, 1, 2, 3, or 4, round the number down. Example: 13 rounded to 1 significant fugue is 10.
3. Zero digits that come after a non zero digit are non significant. Example: 10000 only has 1 significant figure
Calculations:
A) 78 x 92 = 7176
- to round to 1 sig fig we must make all digits after 7 insignificant
- we must also take note of whether the 7 will remain the same or be rounded up
- the digit that comes after is a 1, following the rules of rounding it will remain a 7
The answer for A is 7000
B) 615 x 38 = 23370
- all digits after 2 must be insignificant
- the digit that comes after is a 3, following the rules of rounding the 2 will remain a 2
Answer for B is 20000
C) 423 x 764 = 323172
- all digits after 3 must be insignificant
- the digit that comes after is a 2, following the rules of rounding the 3 will remain a 3
Answer for C is 300000