Now, let's practice subtracting digits in place values. For this activity, you will use an empty ice cube tray, a pack of jellybeans, ten blank index cards, a black marker, a sheet of paper, and a pen. If you want, you can use small pebbles instead of jelly beans.
Write the numbers 0 to 9 on the index cards, one number on each card. Shuffle the cards and put the stack on the table facedown so you can't see the numbers.
Prop up the ice cube tray in front of you on the table so that it's almost vertical. Fill the two top cube compartments with nine jellybeans each. The right cube will represent the ones, and the left cube will represent the tens.
Now pull out a random card from the stack of index cards. From the ones cube, count out jellybeans based on the number written on the card. Place the jellybeans in the cube below that. For example, you pulled out the number 4. Move four jellybeans from the ones cube to the cube below it in the ice cube tray.
Pick out another number from your stack of cards. This time, count out the jellybeans from the tens cube based on the number written on the card. Move the jellybeans to the cube below that.
On the sheet of paper, write down the number 99 at the top. This is the number of jellybeans you started with in the top cubes.
Now write down the number you've pulled out from the index cards. The first number you pulled will go in the ones place. The second number you pulled will go in the tens place. If you pulled out the number 7 first and 4 second, write down the number 47 below 99. Place a minus sign next to 47. You can find the answer by counting the jellybeans that are left in the top two cubes of the ice cube tray.
You can move the jellybeans down the ice cube tray or you can add more jellybeans to it, but be sure that you have nine jellybeans in each cube compartment so you don't miss a number. Have fun counting!
Ready to move on to the next lesson?
Column Subtraction Problems with No Regrouping
