1st Grade Math: 20 Questions (10 Easy · 5 Medium · 5 Hard) with Answers, Explanations & Theory

Answer: C) 6

Explanation. When we count up, each number is one more than the one before it. After 5 comes 6.

Theory — Counting and the successor. Every whole number has a “next number” we get by adding 1. This is called the successor. Counting is built on this idea: 1, 2, 3, … each step is +1.

Answer: C) 2

Explanation. On a number line, 2 sits the furthest to the left, so it is the smallest.

Theory — Comparing whole numbers. Numbers can be ordered from least to greatest. Smaller numbers come earlier when we count up from 0.

Answer: C) 5

Explanation. Touch each dot once as you count: 1, 2, 3, 4, 5.

Theory — One-to-one correspondence. Counting works because we match each object to exactly one number word. The last number you say is how many there are (this is called cardinality).

Answer: B) 5

Explanation. Start at 2 and count up 3 more: 3, 4, 5.

Theory — Addition as joining. Adding two groups means putting them together to find the total. We can also think of it as “counting on” from the first number.

Answer: C) 4

Explanation. Start at 6 and count back 2: 5, 4.

Theory — Subtraction as taking away. Subtracting means removing some objects from a group, or finding “how far apart” two numbers are. It is the inverse (opposite) of addition.

Answer: B) Triangle

Explanation. “Tri-” means three. A triangle has exactly 3 straight sides and 3 corners.

Theory — Defining shapes by attributes. In geometry we describe shapes by the number of sides and corners (vertices), not by their color or size.

Answer: B) 7

Explanation. The numbers are counting down by 1. After 8 comes 7.

Theory — Counting backwards. Just like adding 1 gives the next number, subtracting 1 gives the previous number (the predecessor). This builds the foundation for subtraction.

Answer: C) 5

Explanation. Adding 1 just means “the next number.” After 4 comes 5.

Theory — Adding 1 is the successor. This is the same idea as counting. Every “+1” jumps to the next number on the number line.

Answer: B) 4

Explanation. A square has 4 equal straight sides and 4 corners.

Theory — Classifying quadrilaterals. Any shape with 4 straight sides is a quadrilateral. A square is a special quadrilateral where all 4 sides are the same length and all 4 corners are square corners (right angles).

Answer: B) 5 stars

Explanation. Count each group. The one with 5 stars has the most.

Theory — Comparing sets by counting. To compare two groups, we count each one. The group whose count is the bigger number has more. This connects counting to comparing.

Answer: B) 13

Explanation. A nice trick: take 2 from the 5 and give it to the 8 to make 10. Now you have 10 + 3 = 13.

Theory — Make-a-ten strategy. Since our number system is base 10, decomposing numbers to make a friendly 10 makes addition faster and more accurate. This sets up place value later.

Answer: C) 20

Explanation. 19 has 1 ten and 9 ones. Adding 1 more makes 10 ones, which is another ten — so 2 tens = 20.

Theory — Place value and bundling. In base 10, once you have 10 ones, you “bundle” them into 1 ten. This is the same idea that turns 99 + 1 into 100.

Answer: B) 4

Explanation. Start with 7, take away 3: 7 − 3 = 4.

Theory — Subtraction word problems (take-from). Real-life math comes in stories. Translating words like “fly away,” “lost,” or “ate” into a minus sign is a key first-grade skill.

Answer: B) 4 + 3 = 7

Explanation. Only 4 + 3 actually equals 7. The others give 7, 7, and 4 respectively — none match what is written.

Theory — The equals sign means “same as.” Many kids think = means “the answer comes next.” It really means both sides have the same value. This idea will matter for algebra later.

Answer: A) Hour hand on 3, minute hand on 12

Explanation. “O’clock” means the minute hand points straight up at 12. The hour hand points to the hour — here, 3.

Theory — Telling time to the hour. Clocks measure time using two hands moving at different speeds. The short hand tracks hours; the long hand tracks minutes. Reading them together is an early step toward fractions of an hour.

Answer: C) 7

Explanation. Ask: “6 plus what gets me to 13?” Count up from 6: 7, 8, 9, 10, 11, 12, 13 — that’s 7 jumps.

Theory — Inverse operations. A missing addend can be found with subtraction: 13 − 6 = 7. Addition and subtraction undo each other. This is the seed of solving equations.

Answer: B) 7

Explanation. Break 15 into 10 + 5. Take 8 from the 10 to get 2, then add the leftover 5: 2 + 5 = 7.

Theory — Subtraction with decomposition. Hard subtractions (especially across 10) get easier when you split the larger number using place value. This strategy scales to 2- and 3-digit subtraction later.

Answer: C) 13

Explanation. She lost 4 and ended at 9, so before giving any away she had 9 + 4 = 13.

Theory — Start-unknown problems. When the starting amount is the mystery, we work the problem backwards. These are the hardest 1st-grade word problems because the action (giving away) seems to call for subtraction, but the solution uses addition.

Answer: B) 46

Explanation. 4 tens = 40. Add 6 ones: 40 + 6 = 46.

Theory — Place value. In a 2-digit number, the left digit counts how many tens and the right digit counts how many ones. So 46 means 4 tens + 6 ones, not “four and six.”

Answer: C) 23¢

Explanation. Each dime is 10¢, so 2 dimes = 20¢. Each penny is 1¢, so 3 pennies = 3¢. Total: 20 + 3 = 23¢.

Theory — Coin values and skip counting. Money is a real-world use of place value. Counting dimes by tens (10, 20, 30…) and pennies by ones (21, 22, 23) is exactly the same idea as reading a 2-digit number.