The ability to multiply with the fingers is a valuable skill that has been known to mankind since at least the 15th century. Today every phone has a calculator, but in many cases it is much easier not to take the phone out of your pocket and multiply on your fingers. This method will be useful for students who are just starting to learn multiplication. To successfully use this method, you need to know the multiplication table from one to five. The finger method replaces the multiplication tables with six, seven, eight, nine, and ten.
Part 1 of 2: How to Multiply by Nine
Step 1. Keep your hands in front of you, palms up
Each of the ten fingers corresponds to a number. Count from one to ten, moving from your left to right index finger.
Step 2. Bend the finger whose number you want to multiply by nine
For example, if you want to solve the 9x3 example, then bend the middle finger of your left hand. The middle finger corresponds to the number three, since it is the third finger if you count from one to ten, starting with the left index finger.
Step 3. Count the remaining fingers on the left and right to solve the example
Start by counting the fingers to the left of the curled toe. In this case, you get two. Then count the fingers to the right of the curled toe. You should have seven. The first digit of the answer is 2, and the second digit is 7. It turns out 27!
Step 4. Try to multiply other numbers by nine
How do you multiply 9 by 2 with your fingers? And if 9 by 7?
Part 2 of 2: How to Multiply by Six, Seven, Eight, and Ten
Step 1. Keep your hands with your palms facing your body and your fingers opposite each other
Each finger will correspond to a number again. The little fingers correspond to the number six, the ring fingers correspond to the number seven, the middle fingers correspond to the number eight, the index fingers correspond to the number nine, and the thumbs correspond to the number ten.
Step 2. Touch the fingers that correspond to the desired numbers
For example, to solve the 7x6 example, place your left ring finger on your right pinky. The fingers of the left hand will correspond to the number on the left side of the multiplication sign, and the fingers of the right hand will correspond to the number on the right side of the multiplication sign. Remember that each finger corresponds to a different number, and in this example, the ring finger corresponds to the number seven, and the little finger corresponds to the number six. Therefore, you need to touch these fingers to solve this example.
- You may need to bend the brush uncomfortably!
- Another example: if you need to multiply 9x7, then place your left index finger on the right ring finger.
Step 3. Fold the fingers that are touching, as well as the fingers under them
Now you need to count the touching fingers and the fingers below. They correspond to tens. In our example, we count the ring finger on the left hand, the little finger on the left hand, and the little finger on the right hand. Each of the fingers is counted as the number 10. In our case, the total is 30.
Step 4. Multiply the remaining fingers
Next, add up the number of fingers on each hand, excluding the touching fingers. First, count the number of fingers on the left hand that are above the touching fingers - in this case it is 3. Then count the number of fingers on the right hand that are above the touching fingers - in this case it is 4. 3x4 = 12.
Step 5. Add the two numbers together to find the answer
In this example, you need to add 30 and 12 to get 42. That's right, 7x6 = 42!
Step 6. Multiply by 10 using the same method
For example, if you want to solve the 10x7 example, first place your left thumb on your right ring finger. Count the number of fingers below touching fingers, including touching fingers. You get 7, which equals 70. Then count the number of fingers above the touching fingers on your right and left hand. You will end up with 0 on the left and 3 on the right. Now multiply 3x0, which is 0, and add 70 and 0 to get the answer. That's right, 10x7 = 70!
Step 7. Use this method to multiply by six, seven, eight and ten
How to multiply 8 by 8 using your fingers? What about 7 by 10?