AltR +
' → a → á → apostrophe → acute → áćéíĺńóṕŕśúýźÁĆÉÍĹŃÓṔŔŚÚÝŹ…
` → a → à → grave → grave → àèìòùÀÈÌÒÙ…
, → c → ç → comma → cedilla → çşģķļņÇŞĢĶĻŅ…
^ → a → â → circumflex → circumflex → âêĥîĵôŝûÂÊĤÎĴÔŜÛ…
~ → a → ã → tilde → tilde → ãñõÃÑÕ…
^ → 2 → ² → Superscript 2 (also 0, 1, 3, 4, 5, +, =, (, ), …)
1 → 4 → ¼ → Quarter (similarly half, various quarters, fifths, eighths…)