Worksheet 1Worksheet 2Worksheet 3

The download includes this worksheet followed by the answer key with explanations. In the print dialog choose “Save as PDF” to download.

lessonbunny.com
Name: ______________________________ Date: ______________

Mental Math

Grade 3 · Mathematics · Worksheet 2

  1. Olivia has 245 beads to make bracelets for her friends. She wants to put 35 beads on each bracelet. How many bracelets can Olivia make? Answer: ______________
  2. Liam is organizing his baseball card collection. He has 125 cards and wants to put them into albums. Each album page holds 9 cards. How many complete pages will Liam fill with his baseball cards? Answer: ______________
  3. Emma is looking at a rectangular park on a map. The park is 85 meters long and 60 meters wide. What is the total distance around the outside edge of the park? Use mental math to solve.
    Answer: ______________
  4. 401 - 196 = ? Answer: ______________
  5. Lily is collecting seashells at the beach. On Monday, she found 125 shells. On Tuesday, she found 78 more shells. How many seashells does Lily have in total? Answer: ______________
  6. A rectangular garden is drawn on a grid. The garden is 8 meters long and 5 meters wide. What is the area of the garden in square meters?
    Answer: ______________
lessonbunny.com

Answer Key & Explanations

Mental Math · Grade 3 · Worksheet 2

  1. Olivia has 245 beads to make bracelets for her friends. She wants to put 35 beads on each bracelet. How many bracelets can Olivia make? Answer: 7 Solution: Olivia has 245 beads. Each bracelet uses 35 beads. We need to find 245 ÷ 35.
    Full step-by-step solution

    Step 1: Olivia has 245 beads. Each bracelet uses 35 beads. We need to find 245 ÷ 35. Step 2: Use mental math: 35 × 7 = ? Think of 35 as 30 + 5. Step 3: 30 × 7 = 210 and 5 × 7 = 35. Add them: 210 + 35 = 245. Step 4: So 245 ÷ 35 = 7. The answer is 7 bracelets.

  2. Liam is organizing his baseball card collection. He has 125 cards and wants to put them into albums. Each album page holds 9 cards. How many complete pages will Liam fill with his baseball cards? Answer: 13 Solution: 1. Each album page holds 9 cards. We need to find how many *complete* pages he can fill.
    Full step-by-step solution

    Let's go step-by-step. 1. **Understand the problem** Liam has 125 baseball cards. Each album page holds 9 cards. We need to find how many *complete* pages he can fill. 2. **Set up the division** To find the number of complete pages, divide the total number of cards by the number of cards per page: 125 ÷ 9 3. **Perform the division** 9 × 13 = 117 9 × 14 = 126 Since 126 is more than 125, 14 pages would require more cards than Liam has. So the largest whole number of pages he can completely fill is 13. 4. **Check the remainder** 125 − 117 = 8 cards left over. These 8 cards are not enough to fill another complete page (since 8 < 9). 5. **Conclusion** Liam will fill 13 complete pages with his 125 baseball cards. **Final answer:** 13

  3. Emma is looking at a rectangular park on a map. The park is 85 meters long and 60 meters wide. What is the total distance around the outside edge of the park? Use mental math to solve. Answer: 290 Solution: The distance around a rectangle is its perimeter. Add the length and width: 85 + 60 = 145 (think 80 + 60 = 140, then 140 + 5 = 145).
    Full step-by-step solution

    Step 1: The distance around a rectangle is its perimeter. Add the length and width: 85 + 60 = 145 (think 80 + 60 = 140, then 140 + 5 = 145). Step 2: Double the sum: 145 + 145 = 290 (think 100 + 100 = 200, 45 + 45 = 90, then 200 + 90 = 290). The total distance around the park is 290 meters.

  4. 401 - 196 = ? Answer: 205 Solution: Round 196 up to 200. Step 2: Subtract 401 - 200 = 201. Step 3: Since we subtracted 4 extra (200 - 196 = 4), add 4 back to the result.
    Full step-by-step solution

    Step 1: Round 196 up to 200. Step 2: Subtract 401 - 200 = 201. Step 3: Since we subtracted 4 extra (200 - 196 = 4), add 4 back to the result. Step 4: 201 + 4 = 205. The answer is 205.

  5. Lily is collecting seashells at the beach. On Monday, she found 125 shells. On Tuesday, she found 78 more shells. How many seashells does Lily have in total? Answer: 203 Solution: Lily starts with 125 shells on Monday. On Tuesday, she finds 78 more shells. To find the total, we add the shells from Monday and Tuesday.
    Full step-by-step solution

    Lily starts with 125 shells on Monday. On Tuesday, she finds 78 more shells. To find the total, we add the shells from Monday and Tuesday. Step 1: Write the addition problem. 125 + 78 Step 2: Add the ones place. 5 ones + 8 ones = 13 ones 13 ones = 1 ten and 3 ones Write down 3 in the ones place, carry over 1 to the tens place. Step 3: Add the tens place. 2 tens + 7 tens = 9 tens Plus the carried over 1 ten = 10 tens 10 tens = 1 hundred and 0 tens Write down 0 in the tens place, carry over 1 to the hundreds place. Step 4: Add the hundreds place. 1 hundred + 0 hundreds = 1 hundred Plus the carried over 1 hundred = 2 hundreds Write down 2 in the hundreds place. Step 5: Combine the digits. Hundreds: 2, Tens: 0, Ones: 3 So, 125 + 78 = 203 Answer: Lily has 203 seashells in total.

  6. A rectangular garden is drawn on a grid. The garden is 8 meters long and 5 meters wide. What is the area of the garden in square meters? Answer: 40 Solution: We have a rectangular garden. Its length is 8 meters and its width is 5 meters. We need to find the area in square meters.
    Full step-by-step solution

    Step 1: Understand the problem. We have a rectangular garden. Its length is 8 meters and its width is 5 meters. We need to find the area in square meters. Step 2: Recall the formula for the area of a rectangle. Area = length × width Step 3: Substitute the given values into the formula. Length = 8 meters Width = 5 meters Area = 8 × 5 Step 4: Perform the multiplication. 8 × 5 = 40 Step 5: State the answer with the correct units. The area of the garden is 40 square meters. Final Answer: 40