HP HP-21 - Keying in Exponentsof Ten

Controlling the Display 21
Another way of displaying the answer would be ,
but in normal fix 2 display, you would have seen only
as the displayed part of the answer. So the
display automatically switches to scientific notation display
to let you see the answer.
The HP-21 also switches to scientific notation if the answer is
too large for fixed decimal point display (> 10'°). For example,
solve 1582000 x 1842.
Press Display
1582000
_
_
.
1842
[x]
2914044000.
Fixed
decimal
point
display.
The answer does not overflow, so it remains in fixed notation.
However, solve 1582000 x 18420.
Press Display
1582000
18420(x] Scientific display.
The number is too large for fixed decimal point display, so it is
automatically displayed in scientific notation.
Keying In Exponents of Ten
You can key in numbers multiplied by powers of ten by press-
ing @3 (enter exponent). For example, key in 15.6 trillion
(15.6 x 10'?), and multiply it by 25:
Press Display
15.6
EEX 15.6 00
12 15.6 12 (This means 15.6 x 10'2)
Now Press
1.5600000 13
25 [x] 3.9000000 14
You can save time when keying in exact powers of ten by
pressing [E23 and then pressing the desired power of ten. For
example, key in 1 million (10°) and divide by 52.