(3.24-2.52236)*4589 this result should  have how many significant  figures?
146775
I love when people answer without reading the question.  It should have two significant figures.  You start out with three (from 3.24), but when you subtracted you end up with two because you lose the one directly to the left of the decimal place.  Then when you multiply, you still only have two significant figures.\n\n***Note: The rule that the answer should have the same number of sig. figs. as the number with the fewest only applies to addition and division.  For addition and subtraction the rule is report the same number of figures to the right of the decimal point as the number that has the fewest.  Since 3.24 does not have a 1000ths place, the answer to 3.24-2.52236 shouldn't either (assuming you're following the rules of significant figures rather than simply of arithmetic).  Sorry if that was kind of hard to follow (I need to sleep), but hopefully you get the idea.
500392
5.46*0.3=1.638   1.638-9.86= -8.222  so your answer is -8.222
647455
pi = 3.1415926\n\npi = 3.1416 (fourth decimal place, rounding up)
891988
Multiply that by about 0.458
665207
12.8 & -0.15\n\nEach multiplied by (1/41) gives\n0.312195122 & -0.003658536
1030089
1. 65\n2. 16\n3. 243\n4. 12\n5. 3\n6. 24\n7. 108\n8. 31\n9. 14\n10. $5\n11. 5\n12. 6\n\nI better get best answer for this
807068
(-1.6875) (81) (0.28125) = 38.443359375\n\nIf thats not right, sue me.
494029
Usually you try and keep as many after the decimal as you can, but sometimes it's only practical to keep about 2 or 3 decimal places. And the number of sig figs you end up with, depends on how many you start with. There's all these rules for adding and multiplying, I could never keep them straight. But generally if you keep the same number of sig figs in your answer as you have at the start, that's ok. Like, 12.01 + 15.999 would be 28.009, but you'd round it off to 28.01, the smallest number of sig figs you were given. That's generally the accepted way. I don't know if that made any sense, but that's the best I can do.
649828
3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067
453007
75: 8.660254038\n18: 4.242640687\n24: 4.898979486\n250: 15.8113883\n\nAll values are approximate
592813
2,459,147 and 1/2.\n\nseriously, how would anyone know that?
678134
0.207+0.093+0.031+0.020 = 0.561\n\nor\n\n1-0.439 = 0.561
779807
Yiu would first decide how many decimal places you are going to consider.  The usual is 3.  Then work it from there...;
854222
Those are the right numbers. As you suspected they have too many decimal places, however. To have them correct to 6 decimal places, look at the 7th decimal place. If this is 5 or more, round the 6th decimal up one, otherwise leave it the same and just drop all the numbers after it.\n\nSo for a) the answer would be 1.499975 and for b) it would be 1.499997.
843058
1) 2.01 * 10^2\n\n2) 1.995 * 10^23\n\n3) 5.35 * 10^-4\n\n4) 3.8418 * 10^-7
949695
The correct answer is:\n\n2,432,902,008,176,640,000\n\nYour calculator probably rounded it all little saying your answer is 2.43 with 18 digits after the decimal place.  Genally you'll take the 18 digits as 0 unless some of it is specified originally.\n\nScientific notation is shown two ways:\n2.43 x 10^18\nOR\n2.43E18\n\nFor example\n500 can be stated as 5 x 10^2  OR  5E2\n44200 can be stated as 4.42 x 10^4  OR  4.42E4
1151198
when you multiply 247474747474.5 with Pi, you will get 777777777777.... :)