how can using basic facts help me find 10x2030x40 mentally

Question

I really need help on this for my homework please help please help. I need your help . This is for my math homework

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Answer 1

10×20×30×40: I'm not sure if this what u intent but if it is then all four have 10. 10×10×10×10(4 zeros so 1 and add 4 zero) = 10000. Left with 2×3×4 (omit 1 since it doesn't impact the result) 24×10000=240,000.

 

10x2030x40: factor out the 40 to 4 and 10. 4×2030= 8000+ 120= 8120. The two 10 =100

8120×100= 812000. 

Hope this helps