Place Value Addition: Finding Number Pairs That Sum to 15

Which addition exercise using tens and units results in the number 15?

To determine which addition exercise using tens and units results in the number 15, follow these steps:

• Step 1: Understand the requirements. We are asked to use a combination of:

  • Tens (a multiple of 10).
  • Units (a single-digit number).
  to sum to 15.

• Step 2: Consider possible tens values. Starting from the smallest possible multiple of 10, which is 10, because 20 or more would exceed 15 when adding any units.

• Step 3: Calculate the necessary unit. Subtract the chosen tens value from the total desired sum: $15 - 10 = 5$ So, the necessary units value is 5.

• Step 4: Verify the calculation. Combining the tens and units adds up to: $10 + 5 = 15$

• Step 5: Confirm from choices. Among the given choices, $10 + 5$ is option number 1, and it meets our criteria correctly.

Therefore, the correct addition exercise using tens and units is $10 + 5$, resulting in the number 15.