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Rounding Big Numbers

  • Grade 4
  • Mathematics
  • 4.NBT.A.3
  • Number & Operations in Base Ten
  • Free lesson

Aligned to 4.NBT.A.3 — Common Core State Standards for Mathematics.

What this lesson teaches

To round to a place, look at the digit just to the right of that place. If it is 5 or more, round up; if it is 4 or less, keep the digit the same. Then change all digits to the right to zero.

Worked examples

Example 1

Round 3,472 to the nearest hundred. The hundreds digit is 4. Look one spot to the right at the tens digit: 7. Since 7 is 5 or more, round up: the 4 becomes 5, and digits to the right become zero. Answer: 3,500.

Example 2

Round 8,650 to the nearest thousand. The hundreds digit is 6, which is 5 or more, so round up to 9,000.

Example 3

Round 8,499 to the nearest thousand. Only the hundreds digit decides — it is 4, so round down to 8,000, no matter how big the 99 looks.

Practice questions

  1. Round 2,846 to the nearest hundred.
  2. Round 7,318 to the nearest thousand.
  3. Round 45,672 to the nearest ten thousand.

Watch the lesson

Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.

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En español

Redondear números grandes

Para redondear a una posición, mira la cifra que está justo a la derecha de esa posición. Si es 5 o más, redondea hacia arriba; si es 4 o menos, deja la cifra igual. Luego cambia todas las cifras de la derecha a cero.

Ejemplo 1: Redondea 3,472 a la centena más cercana. La cifra de las centenas es 4. Mira un lugar a la derecha, en las decenas: 7. Como 7 es 5 o más, redondea hacia arriba: el 4 se vuelve 5 y las cifras de la derecha se vuelven cero. Respuesta: 3,500.

Ejemplo 2: Redondea 8,650 al millar más cercano. El dígito de las centenas es 6, que es 5 o más, así que sube a 9,000.

Ejemplo 3: Redondea 8,499 al millar más cercano. Solo decide el dígito de las centenas — es 4, así que baja a 8,000, por grande que se vea el 99.

More Number & Operations in Base Ten lessons

Place Value to a Million and Multi-Digit Arithmetic4.NBT.A.1Read, Write, and Compare Big Numbers4.NBT.A.2Adding and Subtracting Big Numbers4.NBT.B.4Division with Remainders4.NBT.B.6

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