1st Grade Addition Within 20 Worksheet (PDF)

1st Grade math worksheet: Addition Within 20 – Maths PDF

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This addition within 20 worksheet for 1st Grade covers addition within 20 (Common Core 1.OA.A.1, 1.OA.B.3, 1.OA.C.6, 1.OA.C.5), with a free PDF to print.

These 20 problems practice adding within 20 with counters, number lines and word stories. Students count on, make a ten, use doubles and switch the order, as in Common Core 1.OA.C.6.

The first problems are quick facts. The last six are stories with two or three numbers. Draw or use counters if it helps.

Grade 1 · Common Core State Standards: 1.OA.A.1, 1.OA.B.3, 1.OA.C.6, 1.OA.C.5

Addition within 20 worksheet: exercises 1 to 10

Exercise 1 – Count the counters

Blue and orange counters.

Add the blue and orange counters. Write the sum.

Exercise 2 – Count on from the bigger number

Start at 6.

Find \(6 + 2\) by counting on.

Exercise 3 – Add the picture

Maya has 5 stickers. Jamal gives her 3 more. Find \(5 + 3\).

Exercise 4 – Add zero

Find \(9 + 0\).

Exercise 5 – Doubles fact

Two equal groups.

Write the doubles fact for the picture and find the sum.

Exercise 6 – Bigger doubles

Find \(7 + 7\).

Exercise 7 – Switch the order

Write \(3 + 8\) in the other order. Then find the sum.

Exercise 8 – Make a ten with 9

9 blue and 4 orange.

Find \(9 + 4\). Use the frames.

Exercise 9 – Make a ten with 8

Find \(8 + 6\). Make a ten first.

Exercise 10 – Near doubles

Find \(6 + 7\). Use a doubles fact.

Exercises 11 and up

Exercise 11 – Same sum

Write the missing number so the sentence is true: \(7 + 5 = 5 + \text{?}\).

Exercise 12 – Count on 2

Start at 15.

Count on 2 from 15. What number do you reach?

Exercise 13 – Three numbers, make ten

Find \(2 + 7 + 3\).

Exercise 14 – Three numbers, look for a pair

Find \(6 + 4 + 5\).

Exercise 15 – Compare sums

Write <, > or = in the circle: \(8 + 5\) and \(9 + 3\).

Exercise 16 – Sticker story

Priya has 7. She gets 6 more.

Priya has 7 star stickers. Her aunt gives her 6 more. How many stickers does Priya have now?

Exercise 17 – Marbles together

9 blue and 8 orange marbles.

A jar holds 9 blue marbles and 8 orange marbles. How many marbles are in the jar?

Exercise 18 – Muffin doubles

Diego bakes 6 muffins before lunch and 6 muffins after lunch. How many muffins does he bake in all?

Exercise 19 – Pages read

Mei reads 8 pages on Monday, 2 pages on Tuesday and 6 pages on Wednesday. How many pages does she read in all?

Exercise 20 – Is he right?

Noah says \(9 + 5\) has the same sum as \(10 + 4\). Is Noah right? Show how you know.

Key facts behind this addition within 20 worksheet

Key facts

The sum is the total. In 5 + 3 = 8, the sum is 8.
Counting on: start at the bigger number and count up the smaller one.
Make a ten: 8 + 5 = 10 + 3 = 13.
Doubles help: 6 + 6 = 12, so 6 + 7 = 13.
Order does not matter, and adding 0 leaves a number the same.

How to use this addition within 20 worksheet

Work through the exercises in order: they go from simple to challenging. Write every step on paper, then compare with the solutions page and redo any exercise you missed the next day.

All Grade 1 chapters: Grade 1 math.

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