MS-BASIC is for many parts modelled after DEC's PDP-11 BASIC. And PDP-11 BASIC is as well quite related to ECMA-55 Minimal BASIC, so as usual when talking about old BASIC details a look at the fine crafted ECMA-55 specification is helpful.
For PRINTing of number is notes:
Numeric-expressions shall be evaluated to produce a string of
characters consisting of a leading space if the number is po-
sitive or a leading minus-sign if the number is negative fol-
lowed by the decimal representation of the absolute value of
the number and a trailing space. The possible formats for the
decimal representation of a number are the same as those des-
cribed for numeric-constants in 6 and are used as follows.
350 looks like with exactly this formating in mind. A space in front of the number element to make sure that an optional negative sign will not be glued to the text, while no space after, as the number will already produce one.
The standard continues about number output formation:
Each implementation shall define two quantities, a significance-
width d to control the number of significant decimal digits
printed in numeric representations, and an exrad-width e to con-
trol the number of digits printed in the exrad component of a
numeric representation. The value of d shall be at least six
and the value of e shall be at least two.
Each number that can be represented exactly as an integer with
d or fewer decimal digits is output using the implicit point
All other numbers shall be output using either explicit point
unscaled notation or explicit point scaled notation. Numbers
which can be represented with d or fewer digits in the unscaled
format no less accurately than they can be represented in the
scaled format shall be output using the unscaled format. For
example, if d = 6, then 10^(-6) is output as .000001
and 10^(-7) is output as 1.E-7.
Numbers represented in the explicit point unscaled notation shall
be output with up to d significant decimal digits and a full-
stop; trailing zeroes in the fractional part may be omitted.
A number with magnitude less than 1 shall be represented with
no digits to the left of the full-stop. This form requires up
to d+3 characters counting the sign, the full-stop and the
Well, there is mich more to PRINT here - including the TAB() cell argument wich is for example present with DEC and Applesoft BASIC, positioning any following output to a given TAB cell. Which BTW doesn't mean 8 like in terminal speak, but 14 or more, depending on the number printing format used, as a tab cell is supposed to hold a full numeric output. A feature quite handy to print nice lists.
Similar requires to check if there's enough space on the remaining line to output the whole print item or otherwise start a new line first.
If the evaluation of any print-item in a print-list would cause
the length of a nonempty line to exceed the margin, then an
end-of-line is generated prior to the characters generated by
that print-item. Subsequently, if the evaluation of a print-
item generates a string whose length is greater than the mar-
gin, then end-of-lines are inserted after every m characters
in the string, where m is the margin value.
A remarkable point many microcomputer BASICs never implemented - but minis did. Lime many other side effects, programmers may have made use of this, rendering output in a different BASIC different.
In general it is important to keep in mind, that most of the games in 101 BASIC Games weren't first (or at all) developed on a some micro computer, but came from minis with their own BASICs