43: Xiao Zhang counts 48 from right to left, so there are 78-48=30 people left on Xiao Zhang's left, that is, counting from left to right, Xiao Zhang ranks 365,438+0, and Xiao Wang ranks 50 more than Xiao Zhang with 65,438+09, that is, there are 65,438+08 in the middle.

44: 99 minus 1/2 times1/2; Subtract the remaining 1/3 and multiply it by 2/3; Subtract the remaining 1/4, that is, multiply it by 3/4, so finally multiply it by 98/99, and the whole formula is 99 *1/2 * 2/3 * 3/4 * ... * 97/98 * 98/99 = 99 */kloc-0.

46: Folding once means multiplying by 2 to double its thickness, and folding 20 times means multiplying by 20, with a total thickness of 0.01* (11000) * 2 20 =10.49 meters, which is equivalent to 3-4 floors.