Home Models & Strategies · Grade 3 Rounding & Estimating: Six Ways One problem, 367 + 258 = 625, estimated six ways, from the strategies that build the most understanding to the ones that are fastest. put the number between two multiples, then see which one it is nearer to the nearest tento the nearest hundred 370360 365 · halfway 367 past halfway → 370 400300 350 · halfway 367 past halfway → 400 Vertical number line Read this one the midpoint decides, and a number sitting exactly on it always rounds UP past the midpointexactly on the midpoint 360370 365 367 367 is past 365, so it is nearer 370 367 ≈ 370 360370 365 365 365 sits exactly on the midpoint: round UP 365 ≈ 370 the same rule at any place: 250 ≈ 300, 4,500 ≈ 5,000 The halfway mark Read this one look at the digit to the RIGHT of the place you want nearest ten 367 the 7 in the ones place → 5 or more, round up ≈ 370 nearest hundred the 6 in the tens place → 5 or more, round up 367 ≈ 400 The digit rule · the shortcut Read this one round each number, then do the easy problem 367258 →→ 370260 + 630 the estimate: about 630 367 + 258 ≈ 630 Round both, then compute Read this one swap in numbers that are friendly together, not always the nearest ones 367258 →→ 350250 + 600 350 and 250 are easy to add, and 600 is still close to 625 367 + 258 ≈ 600 Compatible numbers Read this one the estimate is how you catch a wrong answer my estimate ≈ 630 my exact answer 625 vs close: the answer makes sense ✓ but if you forgot to carry and got 515 … 515 is nowhere near 630: go back and check an estimate does not give the answer; it guards it Is it reasonable? Read this one