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### Unit 2: Lesson 6

Multiplying decimals

# Decimal multiplication place value

When we rewrite decimal multiplication using fractions, we can use the commutative and associative properties of multiplication to justify how we place the decimal point in the standard multiplication algorithm. Created by Sal Khan.

## Want to join the conversation?

• how did you know all of this
• Isn't their an easier way to multiply decimals?
• yes there is at around he tells you
(1 vote)
• I had to skip from 6th to 8th grade and I got this problem for homework but I don't understand it (a+b)(a2+b2)(a3+b3)(a4+b4)(c+d)(c2+d2)(c3+d3)(c4+d4)=1=9=7=25(1)(2)(3)(4)

First I used the identity
Use this identity to (4) too and simplify (3), we obtain
(a2+b2−ab)(c2+d2−cd)=7
And suppose x=abcd use ac=x/bd,bc=x/ad But then I got stuck... at am
• bruh wat da hail is dat
(1 vote)
• his full name is Abdul Rashid Salim Salman Khan
• Ik this is random but did anybody know that Salman khan (sal) is a famous hindu actor?
• No I did not cool fact
• Wouldn't the answer be 0.04575? BC that would be equal to the ten thousands column in decimals. Maybe I am wrong?🤷‍♀️🤷‍♀️🤷‍♀️
• vhfry f h hy tty ht yty rj h
• I had to skip from 6th to 8th grade and I got this problem for homework but I don't understand it (a+b)(a2+b2)(a3+b3)(a4+b4)(c+d)(c2+d2)(c3+d3)(c4+d4)=1=9=7=25(1)(2)(3)(4)

First I used the identity