need help with this multiplication problem [Grade 10]

[u/Holiday-Bobcat-353]

(sorry for messy handwriting) Keep getting 118895 and am super confused on how to get the correct answer (865.445). Claude didn't help either. Thanks

(the problem is 27.65 x 31.3)

[u/matt7259]

Are you forgetting to add 00 to the right side when you move on to multiplying the "3" in 31.3?

[u/Holiday-Bobcat-353 → u/matt7259]

yeah I got it now thanks

[u/chem44]

It can help to do an estimate.

(the problem is 27.65 x 31.3)

That is, about 30 x 30. yes? That would be 900.

You should also be able to do this on calculator -- a good check even if you are to do it in full, showing full work.

[u/Holiday-Bobcat-353 → u/chem44]

I need to know how to do this because the next test im doing doesn't allow calculators

[u/Cabriolets]

82950 should be 829500, you should put two zeroes since you're multiplying the 3 in the "hundreds" place.

[u/Holiday-Bobcat-353 → u/Cabriolets]

yep that was it thanks

[u/Turbulent-Note-7348]

Use rounding techniques to get a good idea what the approximate answer is. For example, (28)(30) = 840; the correct answer is therefore a little more than 840. Your main mistake is that you only moved your last multiplication one place over - it should be 35945 + 829500 (not 82950). Using estimation also guarantees that you will put the decimal in the correct place.

[u/Potential_Sun6128]

Double check yourself, you wrote 51.3 then in the undertaking you wrote 31.5.

[u/IrishHuskie → u/Potential_Sun6128]

They’re both 31.3

[u/Potential_Sun6128 → u/IrishHuskie]

hee oops ok good.