MSTAR Practice Worksheet

Lesson 2-11: Add and Subtract Decimals

Grade 6 Mathematics · Standard 6.NOS.3

Name: Date:

These are MSTAR-style questions written for this curriculum to rehearse the format. They are not official Maryland assessment items. MSTAR — Maryland's new state test, first given in spring 2027 — uses the same kinds of questions you see here: selected response, select-all, two-part evidence questions, and written responses.

Part A — Skills Check

Warm up with the lesson's core skills — one best answer each.

Question 1Selected response · 1 point

What is 14.6 + 3.85?

A17.45
B18.35
C18.45
D18.55

Question 2Selected response · 1 point

What is 20.3 − 7.48?

A12.18
B12.82
C12.92
D13.82

Question 3Selected response · 1 point

What is 9.05 + 4.7?

A13.12
B13.57
C13.75
D14.75

Question 4Selected response · 1 point

What is 50 − 23.47?

A26.53
B26.63
C27.47
D27.53

Question 5Selected response · 1 point

A student buys items costing $4.59, $12.75, and $3.80. What is the total cost?

A$20.14
B$21.04
C$21.14
D$21.24

Question 6Selected response · 1 point

Case File: A crew member's snack receipt shows $27.60 for dried fruit and $15.45 for protein bars. What is the total on the receipt?

A$42.05
B$42.95
C$43.05
D$43.15

Part B — Test-Format Questions

These match the state test's formats: two-part questions, select-all, and written responses.

Question 7Two-part question

Part A

Find 12.4 + 3.75.

Fill in the bubble next to the one best answer.

A4.99
B15.15
C16.15
D16.79

Part B

Answer Part A before Part B — Part B asks about your reasoning.

Why is a placeholder zero written as 12.40 rather than leaving 12.4?

AIt changes the value of 12.4 to make the addition work.
BZeros must always be written at the end of a decimal.
CIt makes both numbers have the same number of decimal places so each column holds the same place value.
DIt rounds the answer to the nearest hundredth.

Question 8Written response · 2 points

Type II Reasoning: Lining Up the Wrong Edge

Malik computed 9.6 + 0.45 by lining up the RIGHT-hand edges of the digits, as if adding whole numbers. He got 1.41.

Explain Malik's misconception and give the correct sum.

Write your answer in complete sentences. Show or explain your mathematical thinking.

Part C — Show Your Thinking

Answer in writing, the way the state test's constructed responses work.

Question 9Written response · 2 points

A runner's lap times are 2.45 minutes, 2.6 minutes, and 2.38 minutes. Her personal record is 7.5 minutes total. Did she beat her record? Show all your work with decimal alignment and explain.

Write your answer in complete sentences. Show or explain your mathematical thinking.