Grade 1Tens and Ones1.NBT.A.1

Counting and Writing to 120

Count, read and write numbers up to 120.

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In Kindergarten you counted to 100. The count keeps going: 101, 102 … all the way to 120 and beyond.

After 100, the pattern starts again: 101, 102 … 110, 111 … 120.

Key idea

After 100, the count repeats the pattern you know: one hundred one, one hundred two … one hundred ten … one hundred twenty.

Why it works

100 is ten tens. 110 is 100 and 10 more, so it is written 110. Every number from 100 to 199 has 3 digits and starts with 1.

Worked example: Writing 110

Write the number one hundred ten.
  1. One hundred ten is 100 and 10 more.
  2. Count on from 100 by ones: 101, 102 … 110.
  3. It has 3 digits: 110.

Answer: 110

Common mistake

Writing 10010 or 1010 for one hundred ten, by writing down each part you hear. Numbers up to 199 have only 3 digits. Check on the chart: 110 is right below 100.
For grown-ups: Count objects past 100 together, such as pennies or dried beans grouped in tens. Read the numbers on the chart aloud.

Practice

Pass with 3 right answers, the last 2 in a row. Each right answer earns 1 XP.

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Sources and further reading

  • Common Core State Standards for Mathematics, Grade 1, 1.NBT.A.1: count to 120 starting at any number less than 120, and read and write numerals
  • Institute of Education Sciences practice guide: Assisting Students Struggling with Mathematics: Intervention in the Elementary Grades (WWC 2021006)
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