Answer
Let the 10 elements be {a,b,c,d,e,f,g,h,i,j}, then combinations will be:
{aa,ab,ac,ad,ae,af,ag,ah,ai,aj, ba,bb,bc,bd,be,bf,bg,bh,bi,bj, ca,cb,cc,cd,ce,cf,cg,ch,cicaj, da,db,dc,dd,de,df,dg,dh,di,dj,
ea,eb, ec, ed, ef, eg, eh, ei, ej, fa, fb, fc, fd, fe, ff, fg, fh, fi, fj,
ga, gb, gc, gd, ge, gf, gg, gh, gi, gj, ha. hb, hc, hd, he, hf, hg, hi, hj,
ia, ib, ic, id, ie, if, ig, ih, ii, ij, ja, jb, jc, jd, je, jf jg jh, ji, jj}
Mathematically
10C2 = 10! / 2! (10-2)!
= 10! / 2! 8! = 45
Work Step by Step
As given in answer
