Question

number multiplied by 21 to get 438 as an answer..​

Answer 1

Answer:

Multiply with 4 in the end: 5=[2,3], which gives 21=(2+3)*4+1.

Try and add 2 in the end: 18=[3,4]. Not working.

Add 3: 17=[2,4]. Exceptionally bad.

Add 4: 16=[2,3]. Nothing would work.

That addition of 1 in the beginning is rushed at first. So let's try multiplying with the other numbers at the ends. With 2 and 4 it doesn't work, so we can have 21=[1,2,4]*3 or 7=[1,2,4]. The only combination in this variant is to have 7=1+2+4 and thus 21=(1+2+4)*3.

It seems from another answer that even doing this isn't enough. Let's try to factor 21. It is 3*7, maybe 1*3*7 though this doesn't help. Thus, let's make it 3*7. That is, 3*(1+2+4) or (2+1)*(3+4). The first one we've already encountered, the second one is new.

Let's recap what we've found:

1+(2+3)*4

(1+2)*(3+4)

(1+2+4)*3 if you allow us to change the order.

Answer 2

Answer:

solve :- 20.86×21=438.06