Comparing Decimals
Aligned to 4.NF.C.7 — Common Core State Standards for Mathematics.
What this lesson teaches
To compare two decimals, first compare the tenths. If the tenths are equal, compare the hundredths. Adding a zero to fill an empty place, like writing 0.7 as 0.70, makes the two numbers easier to line up.
Worked examples
Example 1
Compare 0.7 and 0.65. Write 0.7 as 0.70 so both have hundredths. Compare tenths: 7 tenths versus 6 tenths. Since 7 > 6, 0.70 > 0.65. So 0.7 > 0.65.
Example 2
Compare 0.3 and 0.29. Write 0.3 as 0.30. Tenths: 3 versus 2, so 0.3 > 0.29 — a longer decimal is not automatically bigger.
Example 3
Compare 0.45 and 0.54. Tenths first: 4 versus 5. Since 4 < 5, 0.45 < 0.54.
Practice questions
- Compare using >, <, or =: 0.4 and 0.40.
- Compare: 0.28 and 0.3.
- Order from least to greatest: 0.5, 0.09, 0.51.
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.
▶ Watch this lessonEn español
Comparar decimales
Para comparar dos decimales, primero compara los décimos. Si los décimos son iguales, compara los centésimos. Agregar un cero para llenar un lugar vacío, como escribir 0.7 como 0.70, hace más fácil alinear los dos números.
Ejemplo 1: Compara 0.7 y 0.65. Escribe 0.7 como 0.70 para que ambos tengan centésimos. Compara los décimos: 7 décimos contra 6 décimos. Como 7 > 6, 0.70 > 0.65. Entonces 0.7 > 0.65.
Ejemplo 2: Compara 0.3 y 0.29. Escribe 0.3 como 0.30. Décimos: 3 contra 2, así que 0.3 > 0.29 — un decimal más largo no es automáticamente mayor.
Ejemplo 3: Compara 0.45 y 0.54. Primero los décimos: 4 contra 5. Como 4 < 5, entonces 0.45 < 0.54.
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