260=1,152,921,504,610,000,000 approx.
To get a more accurate answer use 210=1024=103×1.024.
So 260=(103)6(1+0.024)6.
(1+0.024)6=1+6(0.024)+15(0.024)2+20(0.024)3+15(0.024)4+6(0.024)5+(0.024)6=
1.000000000191102976+
6(0.024+0.000000007962624)+
15(0.000576+0.000000331776)+
20(0.000013824)=
1.000000000191102976+
6(0.024000007962624)+
15(0.000576331776)+
20(0.000013824)=
1.000 000 000 191 102 976+
0.144 000 047 775 744+
0.008 644 976 640+
0.000 276 480
1.152 921 504 606 846 976 (spaces have been used for easier readability).
260=1.152921504606846976×1018=1,152,921,504,606,846,976.