It stays true for digits 1,3,7,9 i.e. 13+31+79+97 = 17+71+39+93 also for 1,2,4,5 with 12+21+45+54 = 14+41+25+52 Maybe there is some pattern. Something simila

It stays true for digits 1,3,7,9 i.e. 13+31+79+97 = 17+71+39+93 also for 1,2,4,5 with 12+21+45+54 = 14+41+25+52 Maybe there is some pattern. Something similar we used to do in school to find answers for multiplication table of 9. We used to write all tables from 1 to 20, recite & them read them back from memory. We would go by writing 9, ten times in ten total rows, like 9 9 .... 9 Then from tenth row come up by writing x (sign of multiplication) 9x Now go down again writing 1,2,3 in each row like 9x1 9x2 .... 9x10 Now come up writing = in every row. Now go down writing digits 0 to 9 like 9x1=0 9x2=1 .... 9x10=9 Now write 0 to 9 again going up, ending up with table. 9x1=09 9x2=18 9x3=27 ..... 9x10=90