Tens and Ones (Place Value)
Aligned to 1.NBT.B.2 — Common Core State Standards for Mathematics.
What this lesson teaches
Two-digit numbers are made of tens and ones. The first digit tells how many groups of ten; the second tells how many extra ones.
Worked examples
Example 1
The number 34 is 3 tens and 4 ones: 30 + 4 = 34.
Example 2
The number 70 is 7 tens and 0 ones. There are no extra ones, so the second digit is 0.
Example 3
In 52 and 25 the same digits appear, but 52 is 5 tens and 2 ones while 25 is only 2 tens and 5 ones. Where a digit sits changes what it is worth.
Practice questions
- How many tens and ones are in 47?
- Build the number that is 5 tens and 2 ones.
- Which is bigger: 6 tens or 60 ones? Explain.
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
Decenas y unidades (valor posicional)
Los números de dos dígitos están formados por decenas y unidades. El primer dígito indica cuántos grupos de diez hay; el segundo indica cuántas unidades sueltas quedan.
Ejemplo 1: El número 34 tiene 3 decenas y 4 unidades: 30 + 4 = 34.
Ejemplo 2: El número 70 tiene 7 decenas y 0 unidades. No hay unidades extra, por eso el segundo dígito es 0.
Ejemplo 3: En 52 y 25 aparecen los mismos dígitos, pero 52 es 5 decenas y 2 unidades mientras que 25 es solo 2 decenas y 5 unidades. El lugar donde está un dígito cambia lo que vale.
More Number & Operations in Base Ten lessons
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