Rounding Strategy
Round to 1 significant figure, then adjust
Multiply/Divide
Round one number up, the other down to compensate
Percentages
10% = move decimal left one place; 5% = half of 10%
Fractions to Know
1/3 ≈ 0.33 | 1/6 ≈ 0.17 | 1/7 ≈ 0.14 | 1/8 = 0.125
Squares to Know
11² = 121 | 12² = 144 | 15² = 225 | 25² = 625
Square Roots
√2 ≈ 1.4 | √3 ≈ 1.7 | √5 ≈ 2.2
