Question 1: Calculate 34 + 27 using mental addition strategies.

Answer: 61

Question 2: Add 46 and 38 by breaking down the numbers into tens and ones and then combining.

Answer: 46 + 38 = (40 + 6) + (30 + 8) = (40 + 30) + (6 + 8) = 70 + 14 = 84

Question 3: If you add 29 to a number and get 61, what was the original number? Explain your reasoning.

Answer: Original number = 61 - 29 = 32

Question 4: Estimate the sum of 49 and 52 mentally, then calculate exactly. Show your mental strategy.

Answer: Estimate: 50 + 50 = 100; Actual: 49 + 52 = (50 - 1) + (50 + 2) = 100 + 1 = 101

Question 5: Add 68 and 27 using a mental strategy involving rounding. Explain your method.

Answer: Round 68 to 70 (+2), add 27: 70 + 27 = 97, but subtract the 2 added earlier: 97 - 2 = 95

Question 6: Calculate 58 + 37 by splitting into tens and units, then combine.

Answer: 58 + 37 = (50 + 8) + (30 + 7) = (50 + 30) + (8 + 7) = 80 + 15 = 95

Question 7: A shop sells 43 apples and 56 oranges. How many pieces of fruit are there in total? Use mental addition.

Answer: 43 + 56 = (40 + 3) + (50 + 6) = (40 + 50) + (3 + 6) = 90 + 9 = 99

Question 8: Add 74 and 29 mentally by rounding to the nearest ten and adjusting.

Answer: 74 + 29 ≈ (70 + 30) = 100, but since 74 is 4 less and 29 is 1 less, total = 100 - 4 - 1 = 95

Question 9: What is 65 + 34? Use mental partitioning to solve.

Answer: 65 + 34 = (60 + 5) + (30 + 4) = (60 + 30) + (5 + 4) = 90 + 9 = 99

Question 10: A cyclist rides 47 km on Monday and 38 km on Tuesday. How many kilometers did they cycle in total? Use mental addition strategies.

Answer: 47 + 38 = (50 - 3) + (40 - 2) = (50 + 40) - (3 + 2) = 90 - 5 = 85

Question 11: Challenge: Calculate 99 + 97 using mental strategies involving rounding and adjustment.

Answer: 99 + 97 ≈ 100 + 100 = 200, but subtract 1 for 99, subtract 3 for 97, total = 200 - 4 = 196

Question 12: Identify and correct the mistake: A student adds 56 and 29 and gets 85. Find the error and give the correct answer.

Answer: Incorrect addition: 56 + 29 = (50 + 6) + (20 + 9) = (50 + 20) + (6 + 9) = 70 + 15 = 85, which is correct. The student made no mistake. If wrong answer was given, the mistake might be in misplacing the digits or in mental calculation.