You can use rounding to figure this problem out. If the number in the ones place is 0 to 4, round down to the nearest tens place; if the number in the ones place in 5 to 9, round up to the nearest tens place.
48 rounds to 50. 42 rounds to 40. 69 rounds to 70. 21 rounds to 20. 52 rounds to 50.
Now use mental math to estimate the cost (50 + 40 + 70 + 20 + 50). Heather will spend about $230.
