Round each number to the nearest hundred and work out the easy sum or difference. If the real answer is close to that estimate, it makes sense.
estimatea close guess
roundchange to a nearby, easier number
nearest hundredthe closest number ending in 00
reasonablemakes sense
Watch for: Rounding to the wrong hundred: 507 to 600. Calling an answer wrong because it isn't exactly the estimate. Counting each small space on the 0 to 1,000 line as 1 or 10 instead of 100.
At home: Before adding up two prices, ask for a quick guess first. Then check the real total against it.
Sample sheet and answer key
Freddie's Frog Pond
Grade 2 · Estimating and checking · 2.NOS.A.5
NameDate
Freddie the frog lives in a busy pond full of bugs, lily pads and friends. Solve each problem to help Freddie out!
Where is the arrow?
Use 0, 500 and 1000 to help. Circle a good guess for each arrow.
A310410930B150560570C120180430
Mark the numbers
Draw an arrow where each number goes.
Mark 440, 240 and 690
Does it make sense?
Round to estimate. Circle whether each answer makes sense.
1
Pip says 467 − 285 = 482.
Estimate:
makes sensedoes not
2
Toby says 417 − 253 = 164.
Estimate:
makes sensedoes not
3
Fern says 758 − 306 = 752.
Estimate:
makes sensedoes not
4
Moss says 314 − 162 = 152.
Estimate:
makes sensedoes not
Sheet
Freddie's Frog Pond
Grade 2 · Estimating and checking · 2.NOS.A.5
Answer key
Freddie the frog lives in a busy pond full of bugs, lily pads and friends. Solve each problem to help Freddie out!
Where is the arrow?
Use 0, 500 and 1000 to help. Circle a good guess for each arrow.
A310410930B150560570C120180430
Mark the numbers
Draw an arrow where each number goes.
Mark 440, 240 and 690
Does it make sense?
Round to estimate. Circle whether each answer makes sense.
1
Pip says 467 − 285 = 482.
Estimate: 200500 − 300 = 200
makes sensedoes not
2
Toby says 417 − 253 = 164.
Estimate: 100400 − 300 = 100
makes sensedoes not
3
Fern says 758 − 306 = 752.
Estimate: 500800 − 300 = 500
makes sensedoes not
4
Moss says 314 − 162 = 152.
Estimate: 100300 − 200 = 100
makes sensedoes not
Answer key
New problems every time, three levels (gentle, core and stretch), themes to pick from, a second page if you want one. Each sheet comes with an answer key and a one-page guide for grown-ups.
