Essential Number Skills: Decimals, Rounding & Real-World Maths
Recurring decimals might look scary, but there's a simple trick to convert them into fractions. When you see 0.0262626..., you multiply by powers of 10 to line up the repeating parts, then subtract to eliminate the recurring bit.
Here's how it works: if x = 0.0262626..., then 10x = 0.2626... and 1000x = 26.2626... Subtracting the second from the third gives you 990x = 26, so x = 26/990. The key is choosing the right powers of 10 based on how many digits repeat.
Rounding to significant figures is all about identifying the important digits. For 2 significant figures, count from the first non-zero digit and round the second one. So 394 becomes 390, 1273 becomes 1300, and 0.618 becomes 0.62.
Quick Tip: When estimating calculations like (40.18 × 6.87) ÷ 0.512, round to simple numbers first: (40 × 7) ÷ 0.5 = 560. This gives you a sensible answer to check against!
Best buy calculations are perfect for real shopping decisions. Simply divide the price by the quantity to find the cost per unit. In the biscuit example, regular costs 9.5p per biscuit whilst large costs 10p per biscuit, making regular the better deal.