lesson
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Imagine you have 48 shiny stickers and you give 15 of them to your best friend. How do you find out how many stickers you have left without counting backward 15 times?
We can write the numbers stacked on top of each other in a vertical subtraction problem.
Lining Up Tens and Ones
Every two-digit number has two parts: the tens digit on the left and the ones digit on the right. When we subtract, we line up the digits so tens stay with tens and ones stay with ones.
📊A clean place-value chart for 48 - 15. Two columns labeled 'Tens' (colored soft blue) and 'Ones' (colored soft orange). Top row shows 4 in Tens, 8 in Ones. Bottom row shows 1 in Tens, 5 in Ones with a minus sign on the far left and a horizontal answer bar below. Beside the numbers, show base-ten visual blocks: 4 ten-rods and 8 unit cubes on top, with 1 ten-rod and 5 unit cubes below. Responsive 350px width card, #ffffff background, rounded corners.
Now that our numbers are neatly lined up in columns, which side do we subtract first?
Step 1: Subtract the Ones
Always start on the right side with the ones column. Here, you take 5 ones away from 8 ones: 8−5=3.
📊Visual diagram focusing on the ones column subtraction. Left column (Tens: 4 and 1) is slightly dimmed. Right column (Ones: 8 and 5) is highlighted with a soft orange glow. Below the line in the ones column, the number 3 appears in bold green. An arrow shows 8 - 5 = 3 with 8 small orange squares and 5 of them crossed out with red X marks, leaving 3 clear squares.
Our ones column gives us 3, but what about the tens sitting on the left side?
Step 2: Subtract the Tens
Next, move to the tens column on the left. Take 1 ten away from 4 tens: 4−1=3.
📊Complete vertical problem fully solved: 48 minus 15 equals 33. The tens column has 4 - 1 = 3 highlighted in soft blue. The ones column has 8 - 5 = 3 highlighted in soft orange. Below the problem, show base-ten visual proof: 4 ten-rods with 1 crossed out = 3 rods (30), and 8 unit cubes with 5 crossed out = 3 cubes (3). Combined final answer badge shows '33 stickers left'.