Let the 2nd number be x. Then the numbers are #1. 1 #2. x #3. 1+x #4. x+(1+x)=x+1+x=1+2x #5. (1+x)+(1+2x)=1+x+1+2x=2+3x #6. (1+2x)+(2+3x)=1+2x+2+3x=3+5x #7. (2+3x)+(3+5x)=2+3x+3+5x=5+8x #8. (3+5x)+(5+8x)=3+5x+5+8x=8+13x #9. (5+8x)+(8+13x)=5+8x+8+13x=13+21x #10. (8+13x)+(13+21x)=8+13x+13+21x=21+34x Since term #10 is 111:Checking, the numbers go , , , , , , , , , Edwin