The ‘2’, ‘5’, ‘7’, and ‘4’ can be derived from the
‘1’ and
‘3’.
2 and 5
The ‘2’ and the ‘5’ take the upper and lower bowls of the ‘3’, respectively, and combine it with a stressed horizontal stroke.
- The ‘2’ is a hard glyph to design. The upper bowl of the ‘3’ has to be extended out all the way to the baseline, where it meets a stressed arm that ends in a beak serif.
- The thickest part of the ‘2’ is the upper right portion of its bowl. The thinnest part is the joint between the bowl and the arm.
- The joint is never a loop (as the ‘2’ is often handwritten), and it almost never bends back out (like it does in some poorly designed sans serif fonts). The vertex is thinner than the arm is.
- The arm of the ‘2’ is slightly wider than the bowl is. It also carries stress, but is geometrically thinner than the stem width for optical reasons.
- The lower bowl of the ‘5’ is almost traced from the lower bowl of the ‘3’. The terminal curves up less, however, and at least in the lining ‘5’, the top part of the bowl angles up before curving down.
- The vertical hairline linking the ‘5’s flag (horizontal stroke) and bowl is sometimes angled slightly to the right.
- The flag of the ‘5’ either has no serif (shown above), or has an overshooting upturn serif.
7
- The ‘7’ receives the flag of the ‘5’, and also the serif and the width of the ‘2’, rotated 180 degrees. The diagonal usually kicks out past the midline of the glyph.
- The diagonal of the ‘7’ is a extreme case of the radial flaring that we’ve seen in letters like ‘v’. It starts out as a hairline and as you get to the bottom, the stroke widens to the stem width. However, some designers like Slimbach want nothing to do with this uncalligraphic convention, so they make the diagonal entirely hairline (though the widening is still there for optical compensation).
- A lot like with the ‘K’, you might need to bend the diagonal geometrically to prevent it from looking bent optically.
- The foot of the ‘7’ should never have a serif. Ever.
4
- The stem of the ‘4’ comes from the ‘1’, or the capital ‘I’ if you don’t feel like shrinking the serifs back down.
- The enclosure of the ‘4’ forms a triangle; its slope is approximately 4:3. Its vertex should receive beveling.
- The diagonal part of the ‘4’ is the thinnest part of the numeral. The cross stroke has a thickness somewhere between the stem thickness and the hairline thickness. The cross stroke extends out about one stem width past the numeral’s stem, and always projects out farther than the figure’s bilateral serif (if it has one).
- The jury is out on whether the ‘4’ should receive serifs. A highly seriffed typeface might place serifs on both the stem and the end of the cross stroke (particularily in the old style forms), while a less aggressively seriffed design might omit both serifs. Most typefaces put a serif on the stem, but not on the cross stroke in the lining form, and omit both in the old style form.
