Page 141 - NUMINO TG_4A
P. 141
09Unit Door Frame Method
jOb ective Use the Door Frame Method to multiply.
1. Textbook Instructions UNIT
Students will learn how to multiply a 3-digit 09 Door Frame Method
number by a 2-digit number.
First, have the students review the multiplication The door frame method uses the shape of Asian door frames to multiply
of a 3-digit number by a 1-digit number and the numbers. Use the door frame method to multiply numbers.
multiplication of 2-digit numbers by using the
Door Frame Method. 123 2 12 3 12 3
Solve 123 2 using the Door Frame Method.
First, draw lines for the first factor, 123. Each 12 3 2 123
place value has a group of vertical lines that
correspond to the digit in that place value. Draw 1, 2, and Draw 2 horizontal 2 \2
The first group has 1 line, the second has 2 3 vertical lines. lines.
lines, and the third has 3 lines. (1st factor) (2nd factor) 24 6 246
The second factor is shown using horizontal
lines. The second factor is 2, so place 2 Count the number of
horizontal lines that cross all the vertical
lines. points where the vertical
In the first group, how many times does a
vertical line intersect a horizontal line? and horizontal lines meet.
Twice.
In the second group, how many times does a 213 3 = 639 134 2 = 268
vertical line intersect a horizontal line? 2 13
Four times. 13 4
In the third group, how many times does a 3
vertical line intersect a horizontal line? 2
Six times.
123 6 is 246. 212 4 = 848 332 3 = 996
21 2 33 2
4 3
74
2. Build Understanding
Door Frame Method and vertical form
After finding each product using the Door Frame Method, have the students check their answers by
multiplying in the vertical form.
Students will be able to confirm that there are various ways to solve multiplication problems.
Example: Find the product of 123 3 by using the vertical form.
1 23 1 23 123 1 23
2 222
6 666
40 4 0 40
200 2 00
2 46
124 NUMINO Teacher s Guide
jOb ective Use the Door Frame Method to multiply.
1. Textbook Instructions UNIT
Students will learn how to multiply a 3-digit 09 Door Frame Method
number by a 2-digit number.
First, have the students review the multiplication The door frame method uses the shape of Asian door frames to multiply
of a 3-digit number by a 1-digit number and the numbers. Use the door frame method to multiply numbers.
multiplication of 2-digit numbers by using the
Door Frame Method. 123 2 12 3 12 3
Solve 123 2 using the Door Frame Method.
First, draw lines for the first factor, 123. Each 12 3 2 123
place value has a group of vertical lines that
correspond to the digit in that place value. Draw 1, 2, and Draw 2 horizontal 2 \2
The first group has 1 line, the second has 2 3 vertical lines. lines.
lines, and the third has 3 lines. (1st factor) (2nd factor) 24 6 246
The second factor is shown using horizontal
lines. The second factor is 2, so place 2 Count the number of
horizontal lines that cross all the vertical
lines. points where the vertical
In the first group, how many times does a
vertical line intersect a horizontal line? and horizontal lines meet.
Twice.
In the second group, how many times does a 213 3 = 639 134 2 = 268
vertical line intersect a horizontal line? 2 13
Four times. 13 4
In the third group, how many times does a 3
vertical line intersect a horizontal line? 2
Six times.
123 6 is 246. 212 4 = 848 332 3 = 996
21 2 33 2
4 3
74
2. Build Understanding
Door Frame Method and vertical form
After finding each product using the Door Frame Method, have the students check their answers by
multiplying in the vertical form.
Students will be able to confirm that there are various ways to solve multiplication problems.
Example: Find the product of 123 3 by using the vertical form.
1 23 1 23 123 1 23
2 222
6 666
40 4 0 40
200 2 00
2 46
124 NUMINO Teacher s Guide
