Count to 120

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Answer Key & Explanations

Count to 120 · Grade 1 · Worksheet 3

1. 99, 100, __, 102 Answer: 101 Solution: Look at the pattern: 99, 100, __, 102. The numbers are increasing by 1 each time. Start at 99.
   Full step-by-step solution

   Step 1: Look at the pattern: 99, 100, __, 102. The numbers are increasing by 1 each time. Step 2: Start at 99. Add 1 to get 100. Step 3: Add 1 to 100 to get 101. Step 4: Check: 101 + 1 = 102, which matches the last number. The missing number is 101.

2. What number comes after 116? Answer: 117 Solution: Start at 116. Count forward by 1: 116, 117. The number that comes after 116 is 117.
   Full step-by-step solution

   Step 1: Start at 116. Step 2: Count forward by 1: 116, 117. Step 3: The number that comes after 116 is 117. The answer is 117.

3. What number comes after 79? Answer: 80 Solution: Start at 79. Count forward by 1: 79, 80. The number that comes after 79 is 80.
   Full step-by-step solution

   Step 1: Start at 79. Step 2: Count forward by 1: 79, 80. Step 3: The number that comes after 79 is 80. The answer is 80.

4. 25 + 17 = ? Answer: 42 Solution: Write the numbers vertically, aligning the ones and tens places. 25 + 17 Add the digits in the ones column (rightmost column). 5 + 7 = 12 Since 12 is a two-digit number, we separate it into 10 and 2.
   Full step-by-step solution

   Let's add 25 and 17 step-by-step. Step 1: Write the numbers vertically, aligning the ones and tens places. 25 + 17 Step 2: Add the digits in the ones column (rightmost column). 5 + 7 = 12 Step 3: Since 12 is a two-digit number, we separate it into 10 and 2. We write down the 2 in the ones place of the answer and carry over the 1 (which represents 10) to the tens column. Step 4: Now add the digits in the tens column, including the carry-over. 2 + 1 + 1 = 4 (The 2 is from 25, the 1 is from 17, and the last 1 is the carry-over from the ones column.) Step 5: Write the result from the tens column next to the 2 from the ones column. The answer is 42. So, 25 + 17 = 42.

5. 45 + 23 = ? Answer: 68 Solution: Write the numbers vertically, aligning the ones and tens columns. 45 + 23 Add the digits in the ones column first. 5 (ones from 45) + 3 (ones from 23) = 8 Write 8 in the ones place of the answer.
   Full step-by-step solution

   Let's add 45 and 23 step-by-step. Step 1: Write the numbers vertically, aligning the ones and tens columns. 45 + 23 Step 2: Add the digits in the ones column first. 5 (ones from 45) + 3 (ones from 23) = 8 Write 8 in the ones place of the answer. Step 3: Add the digits in the tens column. 4 (tens from 45) + 2 (tens from 23) = 6 Write 6 in the tens place of the answer. Step 4: Combine the results from the tens and ones columns. The tens column gave 6, and the ones column gave 8, so together they make 68. Therefore, 45 + 23 = 68.

6. Emma is collecting shells at the beach. She finds 12 white shells and 8 brown shells. How many shells does Emma have in total? Answer: 20 Solution: Emma has 12 white shells. Emma has 8 brown shells. Add the white shells and brown shells together: 12 + 8 12 + 8 = 20 Emma has 20 shells in total.
   Full step-by-step solution

   Step 1: Emma has 12 white shells. Step 2: Emma has 8 brown shells. Step 3: Add the white shells and brown shells together: 12 + 8 Step 4: 12 + 8 = 20 Emma has 20 shells in total.

7. 120 - 60 = ? Answer: 60 Solution: Start with the number 120. Subtract 60 from 120. 120 - 60 = 60.
   Full step-by-step solution

   Step 1: Start with the number 120. Step 2: Subtract 60 from 120. Step 3: 120 - 60 = 60. The answer is 60.

8. 25 + 15 = ? Answer: 40 Solution: Write the problem clearly. 25 + 15 Start by adding the numbers in the ones place (the rightmost digits). The ones digit of 25 is 5.
   Full step-by-step solution

   Let's add 25 and 15 step-by-step. Step 1: Write the problem clearly. 25 + 15 Step 2: Start by adding the numbers in the ones place (the rightmost digits). The ones digit of 25 is 5. The ones digit of 15 is 5. Add them: 5 + 5 = 10. Step 3: Handle the result from Step 2. Since 10 is a two-digit number, we write down the 0 in the ones place of the answer and carry over the 1 to the tens place. Step 4: Now add the numbers in the tens place, including the carry-over. The tens digit of 25 is 2. The tens digit of 15 is 1. Add them: 2 + 1 = 3. Now add the carried-over 1: 3 + 1 = 4. Step 5: Combine the results. The tens place is 4 and the ones place is 0. So the final answer is 40. Therefore, 25 + 15 = 40.

9. 120 - 15 = ? Answer: 105 Solution: Start with 120. Subtract 10 first: 120 - 10 = 110. Then subtract 5 more: 110 - 5 = 105.
   Full step-by-step solution

   Step 1: Start with 120. Step 2: Subtract 10 first: 120 - 10 = 110. Step 3: Then subtract 5 more: 110 - 5 = 105. Step 4: So, 120 - 15 = 105. The answer is 105.

10. Alex is counting seashells. Alex says, 'I have 44 seashells.' Then Alex finds 6 more. What number comes right after 44 when Alex counts from 44 to 44 + 6? Answer: 45 Solution: We need to find the next number after 44. When counting forward, the next number is one more. 44 + 1 = 45.
    Full step-by-step solution

    We need to find the next number after 44. When counting forward, the next number is one more. 44 + 1 = 45. So the number that comes after 44 is 45.