Page 179 - NUMINO TG_3A
P. 179
11Unit The Magic Rods
jOb ective Use Napier’s rods to multiply.
1. Textbook Instructions UNIT
11 The Magic Rods
Have students learn how to multiply a 2-digit In the 17th century, an English mathematician named 38
number by a 1-digit number using Napier’s John Napier invented a tool called Napier’s Rods
rods. to make multiplication faster and easier. 1 00
38
2 01
66
3 02
94
4 13
22
Before starting this unit, explain to 38 5 14
50
1 00 6 14
38 85
students about Napier’s rods and 2 01 7 25
66 16
02 8 26
94 44
3
how to use them to multiply. 9 27
72
4 13
22 Napier’s Rods
Refer to . 5 14
50
6 14
88
How to calculate 38 4 using 7 25
Napier’s method. 16
8 26
44
9 27
72
38 Use Napier’s Rods to multiply.
Use the rods with 3 and 8 at 1 3 4 38 ^ 4 152
the top to calculate 38 4. 2 2 38
34
Place the rods side by 3 48 4 2 38 38
side as shown in the 1 34 1 34
picture on the right. 38 Multiply the ones.
Take off the pieces 22 22
you can use to 1 32 4
calculate 3 4 and 8 2 Multiply the tens. 152
4. 152 Add the numbers in
the diagonal.
Draw diagonal lines. Then add the 5 7 2 4
numbers from the back. 1 1 3
2
5 3 6 2 8
1
17 1 192
100
2. Build Understanding
Napier’s rods
Napier’s rods are tools used to simplify calculations. It is also called the Napier’s bones. There are wooden
sticks, where each rod is divided into 10 square pieces (horizontal and vertical).
The great thing about using Napier’s rods is that it gives you an easier way to multiply large numbers. John
Napier was the inventor of this tool and he wrote about it in a book called Rabdologiae in 1617.
162 NUMINO Teacher s Guide
jOb ective Use Napier’s rods to multiply.
1. Textbook Instructions UNIT
11 The Magic Rods
Have students learn how to multiply a 2-digit In the 17th century, an English mathematician named 38
number by a 1-digit number using Napier’s John Napier invented a tool called Napier’s Rods
rods. to make multiplication faster and easier. 1 00
38
2 01
66
3 02
94
4 13
22
Before starting this unit, explain to 38 5 14
50
1 00 6 14
38 85
students about Napier’s rods and 2 01 7 25
66 16
02 8 26
94 44
3
how to use them to multiply. 9 27
72
4 13
22 Napier’s Rods
Refer to . 5 14
50
6 14
88
How to calculate 38 4 using 7 25
Napier’s method. 16
8 26
44
9 27
72
38 Use Napier’s Rods to multiply.
Use the rods with 3 and 8 at 1 3 4 38 ^ 4 152
the top to calculate 38 4. 2 2 38
34
Place the rods side by 3 48 4 2 38 38
side as shown in the 1 34 1 34
picture on the right. 38 Multiply the ones.
Take off the pieces 22 22
you can use to 1 32 4
calculate 3 4 and 8 2 Multiply the tens. 152
4. 152 Add the numbers in
the diagonal.
Draw diagonal lines. Then add the 5 7 2 4
numbers from the back. 1 1 3
2
5 3 6 2 8
1
17 1 192
100
2. Build Understanding
Napier’s rods
Napier’s rods are tools used to simplify calculations. It is also called the Napier’s bones. There are wooden
sticks, where each rod is divided into 10 square pieces (horizontal and vertical).
The great thing about using Napier’s rods is that it gives you an easier way to multiply large numbers. John
Napier was the inventor of this tool and he wrote about it in a book called Rabdologiae in 1617.
162 NUMINO Teacher s Guide
