Question

para hacer una estimación, puedes redondear números de 3 dígitos a la centena más cercana y redondear números de 4 dígitos al millar más cercano.
usa el redondeo para estimar 7×215.
primero, redondea 215 a la centena más cercana.
215
200 250 300
215 se redondea a 200.
luego, multiplica. 7×200 = 1,400
por tanto, 7×215 es aproximadamente 1,400.
comprueba si 2,885×4 = 11,540 es razonable.
primero, redondea 2,885 al millar más cercano.
2,885 se redondea a 3,000.
luego, multiplica.
3,000×4 = 12,000
por tanto, 2,885×4 es aproximadamente 12,000.
11,540 es una respuesta razonable.
para 1 a 6, estima los productos.

1. 4×279

redondea 279 a
4× =

1. 9×4,720

redondea 4,720 a
9× =

1. 8×89

redondea 89 a
8× =

1. 183×4
2. 3×1,675
3. 8,210×2

para 7 a 9, haz una estimación para comprobar si la respuesta es razonable.

1. 8×578 = 4,624

redondea 578 a
8× =
razonable no es razonable.

1. 3×8,230 = 2,469

redondea 8,230 a
3× =
razonable no es razonable.

1. 7×289 = 2,023

redondea 289 a
7× =
razonable no es razonable.
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tema 3 | lección 3 - 2 29

Explanation:

Step1: Estimate 4×279

Round 279 to the nearest hundred. 279 is closer to 300. So 4×300 = 1200.

Step2: Estimate 9×4720

Round 4720 to the nearest thousand. 4720 is closer to 5000. So 9×5000 = 45000.

Step3: Estimate 8×89

Round 89 to the nearest ten. 89 is closer to 90. So 8×90 = 720.

Step4: Estimate 183×4

Round 183 to the nearest hundred. 183 is closer to 200. So 4×200 = 800.

Step5: Estimate 3×1675

Round 1675 to the nearest thousand. 1675 is closer to 2000. So 3×2000 = 6000.

Step6: Estimate 8210×2

Round 8210 to the nearest thousand. 8210 is closer to 8000. So 8000×2 = 16000.

Step7: Check 8×578 = 4624

Round 578 to the nearest hundred. 578 is closer to 600. 8×600 = 4800. Since 4624 is close to 4800, it is reasonable.

Step8: Check 3×8230 = 2469

Round 8230 to the nearest thousand. 8230 is closer to 8000. 3×8000 = 24000. Since 2469 is not close to 24000, it is not reasonable.

Step9: Check 7×289 = 2023

Round 289 to the nearest hundred. 289 is closer to 300. 7×300 = 2100. Since 2023 is close to 2100, it is reasonable.

Answer:

1. 4×300 = 1200
2. 9×5000 = 45000
3. 8×90 = 720
4. 4×200 = 800
5. 3×2000 = 6000
6. 8000×2 = 16000
7. 8×600 = 4800, Reasonable
8. 3×8000 = 24000, Not reasonable
9. 7×300 = 2100, Reasonable