1.0000000000000000001
1.000000000000000000

It's precision of display....

Have you learned C or C++? It's like:

printf("%.3d",1.000001);

If you mean:

1.0000000000000000001==1.0000000000000000000

It's because the default precision has only ten numbers, You need usesetPrecision or like

1.0000000000000000001`22==1.0000000000000000000`22

There is refered in Possible Issues (https://reference.wolfram.com/language/ref/Equal.html)

(If you think my English is poor, it's because I'm not native English speaker....

1.0000000000000000001
1.000000000000000000

It's precision of display....

Have you learned C or C++? It's like:

printf("%.3d",1.000001);

If you mean:

1.0000000000000000001==1.0000000000000000000

It's because the default precision has only ten numbers, You need usesetPrecision or like

1.0000000000000000001`22==1.0000000000000000000`22

There is refered in Possible Issues (https://reference.wolfram.com/language/ref/Equal.html)

It's mean setPrecision[y,30] make Precision[y] from 10 to 30... In other way, the infinite precision is you can set some value's precision infinite, not any of them is infinite defaultly.

(If you think my English is poor, it's because I'm not native English speaker....

1.0000000000000000001
1.000000000000000000

It's precision of display....

Have you learned C or C++? It's like:

printf("%.3d",1.000001);

1.0000000000000000001
1.000000000000000000

It's precision of display....

Have you learned C or C++? It's like:

printf("%.3d",1.000001);

If you mean:

1.0000000000000000001==1.0000000000000000000

It's because the default precision has only ten numbers, You need usesetPrecision or like

1.0000000000000000001`22==1.0000000000000000000`22

There is refered in Possible Issues (https://reference.wolfram.com/language/ref/Equal.html)

(If you think my English is poor, it's because I'm not native English speaker....