1) 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97
= 5 + 5 + 23 + 23 + 97 + 97
= 2.(5+23+97)
= 2. 125
= 250
2) 100+98+96+94+....+2-97-95-93-...-3-1
= 100 +(98-97) +(96-95) +(94-93)+...+(2-1)
= 100 +1+1+1+...+1 (98 : 2 =49 số 1)
= 100 + 49
= 149
3) 1-2-3+4+5-6-7+8+9-...+2012+2013-2014-2015+2016+2017
= (1-2-3+4) +(5-6-7+8)+....+(2013-2014-2015+2016)+2017
= 0+0+...+0+2017
= 2017